diff --git a/instrumentation/src/androidTest/java/com/bumptech/glide/ErrorHandlingTest.java b/instrumentation/src/androidTest/java/com/bumptech/glide/ErrorHandlingTest.java
index 402984f1c1..2e4898227a 100644
--- a/instrumentation/src/androidTest/java/com/bumptech/glide/ErrorHandlingTest.java
+++ b/instrumentation/src/androidTest/java/com/bumptech/glide/ErrorHandlingTest.java
@@ -49,7 +49,7 @@ public class ErrorHandlingTest {
   private Context context;
 
   @Before
-  public void setUp() throws InterruptedException {
+  public void setUp() {
     MockitoAnnotations.initMocks(this);
     context = InstrumentationRegistry.getTargetContext();
   }
@@ -82,8 +82,7 @@ public void load_whenEncoderFails_callsUncaughtThrowableStrategy() {
   }
 
   @Test
-  public void load_whenLoadSucceeds_butEncoderFails_doesNotCallOnLoadFailed()
-      throws InterruptedException {
+  public void load_whenLoadSucceeds_butEncoderFails_doesNotCallOnLoadFailed() {
     WaitForErrorStrategy strategy = new WaitForErrorStrategy();
     Glide.init(context,
         new GlideBuilder()
@@ -110,8 +109,7 @@ public void load_whenLoadSucceeds_butEncoderFails_doesNotCallOnLoadFailed()
   }
 
   @Test
-  public void clearRequest_withError_afterPrimaryFails_clearsErrorRequest()
-      throws InterruptedException {
+  public void clearRequest_withError_afterPrimaryFails_clearsErrorRequest() {
     WaitModel<Integer> errorModel = WaitModelLoader.Factory.waitOn(ResourceIds.raw.canonical);
 
     FutureTarget<Drawable> target =
@@ -151,6 +149,7 @@ private static final class FailEncoder implements ResourceEncoder<Bitmap> {
 
     static final RuntimeException TO_THROW = new RuntimeException();
 
+    @NonNull
     @Override
     public EncodeStrategy getEncodeStrategy(@NonNull Options options) {
       return EncodeStrategy.TRANSFORMED;
diff --git a/integration/gifencoder/src/main/java/com/bumptech/glide/integration/gifencoder/ReEncodingGifResourceEncoder.java b/integration/gifencoder/src/main/java/com/bumptech/glide/integration/gifencoder/ReEncodingGifResourceEncoder.java
index e8a390fddb..0d67e6fd72 100644
--- a/integration/gifencoder/src/main/java/com/bumptech/glide/integration/gifencoder/ReEncodingGifResourceEncoder.java
+++ b/integration/gifencoder/src/main/java/com/bumptech/glide/integration/gifencoder/ReEncodingGifResourceEncoder.java
@@ -53,7 +53,8 @@ public class ReEncodingGifResourceEncoder implements ResourceEncoder<GifDrawable
   public static final Option<Boolean> ENCODE_TRANSFORMATION =
       Option.disk(KEY_ENCODE_TRANSFORMATION, false, new Option.CacheKeyUpdater<Boolean>() {
         @Override
-        public void update(byte[] keyBytes, Boolean value, MessageDigest messageDigest) {
+        public void update(@NonNull byte[] keyBytes, @NonNull Boolean value,
+            @NonNull MessageDigest messageDigest) {
           if (value) {
             messageDigest.update(keyBytes);
           }
@@ -81,6 +82,7 @@ public ReEncodingGifResourceEncoder(@NonNull Context context, @NonNull BitmapPoo
     this.factory = factory;
   }
 
+  @NonNull
   @Override
   public EncodeStrategy getEncodeStrategy(@NonNull Options options) {
     Boolean encodeTransformation = options.get(ENCODE_TRANSFORMATION);
@@ -213,7 +215,8 @@ AnimatedGifEncoder buildEncoder() {
       return new AnimatedGifEncoder();
     }
 
-    Resource<Bitmap> buildFrameResource(Bitmap bitmap, BitmapPool bitmapPool) {
+    @NonNull
+    Resource<Bitmap> buildFrameResource(@NonNull Bitmap bitmap, @NonNull BitmapPool bitmapPool) {
       return new BitmapResource(bitmap, bitmapPool);
     }
   }
diff --git a/library/src/main/java/com/bumptech/glide/load/ImageHeaderParser.java b/library/src/main/java/com/bumptech/glide/load/ImageHeaderParser.java
index 52463e74a7..b188c4df34 100644
--- a/library/src/main/java/com/bumptech/glide/load/ImageHeaderParser.java
+++ b/library/src/main/java/com/bumptech/glide/load/ImageHeaderParser.java
@@ -1,5 +1,6 @@
 package com.bumptech.glide.load;
 
+import android.support.annotation.NonNull;
 import com.bumptech.glide.load.engine.bitmap_recycle.ArrayPool;
 import java.io.IOException;
 import java.io.InputStream;
@@ -10,9 +11,9 @@
  */
 public interface ImageHeaderParser {
   /**
-   * A constant indicating we were unable to parse the orientation from the image either because
-   * no exif segment containing orientation data existed, or because of an I/O error attempting to
-   * read the exif segment.
+   * A constant indicating we were unable to parse the orientation from the image either because no
+   * exif segment containing orientation data existed, or because of an I/O error attempting to read
+   * the exif segment.
    */
   int UNKNOWN_ORIENTATION = -1;
 
@@ -32,10 +33,9 @@ enum ImageType {
     WEBP_A(true),
     /** WebP type without alpha. */
     WEBP(false),
-    /**
-     * Unrecognized type.
-     */
+    /** Unrecognized type. */
     UNKNOWN(false);
+
     private final boolean hasAlpha;
 
     ImageType(boolean hasAlpha) {
@@ -47,8 +47,11 @@ public boolean hasAlpha() {
     }
   }
 
-  ImageType getType(InputStream is) throws IOException;
-  ImageType getType(ByteBuffer byteBuffer) throws IOException;
+  @NonNull
+  ImageType getType(@NonNull InputStream is) throws IOException;
+
+  @NonNull
+  ImageType getType(@NonNull ByteBuffer byteBuffer) throws IOException;
 
   /**
    * Parse the orientation from the image header. If it doesn't handle this image type (or this is
@@ -57,6 +60,8 @@ public boolean hasAlpha() {
    * @return The exif orientation if present or -1 if the header couldn't be parsed or doesn't
    * contain an orientation
    */
-  int getOrientation(InputStream is, ArrayPool byteArrayPool) throws IOException;
-  int getOrientation(ByteBuffer byteBuffer, ArrayPool byteArrayPool) throws IOException;
+  int getOrientation(@NonNull InputStream is, @NonNull ArrayPool byteArrayPool) throws IOException;
+
+  int getOrientation(@NonNull ByteBuffer byteBuffer, @NonNull ArrayPool byteArrayPool)
+      throws IOException;
 }
diff --git a/library/src/main/java/com/bumptech/glide/load/ImageHeaderParserUtils.java b/library/src/main/java/com/bumptech/glide/load/ImageHeaderParserUtils.java
index d790108ec0..97930be119 100644
--- a/library/src/main/java/com/bumptech/glide/load/ImageHeaderParserUtils.java
+++ b/library/src/main/java/com/bumptech/glide/load/ImageHeaderParserUtils.java
@@ -1,5 +1,6 @@
 package com.bumptech.glide.load;
 
+import android.support.annotation.NonNull;
 import android.support.annotation.Nullable;
 import com.bumptech.glide.load.ImageHeaderParser.ImageType;
 import com.bumptech.glide.load.engine.bitmap_recycle.ArrayPool;
@@ -20,8 +21,9 @@ public final class ImageHeaderParserUtils {
   private ImageHeaderParserUtils() { }
 
   /** Returns the ImageType for the given InputStream. */
-  public static ImageType getType(List<ImageHeaderParser> parsers, @Nullable InputStream is,
-      ArrayPool byteArrayPool) throws IOException {
+  @NonNull
+  public static ImageType getType(@NonNull List<ImageHeaderParser> parsers,
+      @Nullable InputStream is, @NonNull ArrayPool byteArrayPool) throws IOException {
     if (is == null) {
       return ImageType.UNKNOWN;
     }
@@ -48,7 +50,9 @@ public static ImageType getType(List<ImageHeaderParser> parsers, @Nullable Input
   }
 
   /** Returns the ImageType for the given ByteBuffer. */
-  public static ImageType getType(List<ImageHeaderParser> parsers, @Nullable ByteBuffer buffer)
+  @NonNull
+  public static ImageType getType(@NonNull List<ImageHeaderParser> parsers,
+      @Nullable ByteBuffer buffer)
       throws IOException {
     if (buffer == null) {
       return ImageType.UNKNOWN;
@@ -66,9 +70,11 @@ public static ImageType getType(List<ImageHeaderParser> parsers, @Nullable ByteB
     return ImageType.UNKNOWN;
   }
 
-  /** Returns the orientation for the given InputStream. */
-  public static int getOrientation(List<ImageHeaderParser> parsers, @Nullable InputStream is,
-      ArrayPool byteArrayPool) throws IOException {
+  /**
+   * Returns the orientation for the given InputStream.
+   */
+  public static int getOrientation(@NonNull List<ImageHeaderParser> parsers,
+      @Nullable InputStream is, @NonNull ArrayPool byteArrayPool) throws IOException {
     if (is == null) {
       return ImageHeaderParser.UNKNOWN_ORIENTATION;
     }
diff --git a/library/src/main/java/com/bumptech/glide/load/Key.java b/library/src/main/java/com/bumptech/glide/load/Key.java
index 2e7fd07f84..f78a7b168c 100644
--- a/library/src/main/java/com/bumptech/glide/load/Key.java
+++ b/library/src/main/java/com/bumptech/glide/load/Key.java
@@ -24,9 +24,17 @@ public interface Key {
    */
   void updateDiskCacheKey(@NonNull MessageDigest messageDigest);
 
+  /**
+   * For caching to work correctly, implementations <em>must</em> implement this method and
+   * {@link #hashCode()}.
+   */
   @Override
   boolean equals(Object o);
 
+  /**
+   * For caching to work correctly, implementations <em>must</em> implement this method and
+   * {@link #equals(Object)}.
+   */
   @Override
   int hashCode();
 }
diff --git a/library/src/main/java/com/bumptech/glide/load/MultiTransformation.java b/library/src/main/java/com/bumptech/glide/load/MultiTransformation.java
index aaac6cd684..6b1d038f2f 100644
--- a/library/src/main/java/com/bumptech/glide/load/MultiTransformation.java
+++ b/library/src/main/java/com/bumptech/glide/load/MultiTransformation.java
@@ -17,7 +17,7 @@ public class MultiTransformation<T> implements Transformation<T> {
 
   @SafeVarargs
   @SuppressWarnings("varargs")
-  public MultiTransformation(Transformation<T>... transformations) {
+  public MultiTransformation(@NonNull Transformation<T>... transformations) {
     if (transformations.length == 0) {
       throw new IllegalArgumentException(
           "MultiTransformation must contain at least one Transformation");
@@ -25,7 +25,7 @@ public MultiTransformation(Transformation<T>... transformations) {
     this.transformations = Arrays.asList(transformations);
   }
 
-  public MultiTransformation(Collection<? extends Transformation<T>> transformationList) {
+  public MultiTransformation(@NonNull Collection<? extends Transformation<T>> transformationList) {
     if (transformationList.isEmpty()) {
       throw new IllegalArgumentException(
           "MultiTransformation must contain at least one Transformation");
diff --git a/library/src/main/java/com/bumptech/glide/load/Option.java b/library/src/main/java/com/bumptech/glide/load/Option.java
index f6b2e1dbc5..561264871f 100644
--- a/library/src/main/java/com/bumptech/glide/load/Option.java
+++ b/library/src/main/java/com/bumptech/glide/load/Option.java
@@ -1,5 +1,6 @@
 package com.bumptech.glide.load;
 
+import android.support.annotation.NonNull;
 import android.support.annotation.Nullable;
 import com.bumptech.glide.util.Preconditions;
 import java.security.MessageDigest;
@@ -26,7 +27,8 @@
 public final class Option<T> {
   private static final CacheKeyUpdater<Object> EMPTY_UPDATER = new CacheKeyUpdater<Object>() {
     @Override
-    public void update(byte[] keyBytes, Object value, MessageDigest messageDigest) {
+    public void update(@NonNull byte[] keyBytes, @NonNull Object value,
+        @NonNull MessageDigest messageDigest) {
       // Do nothing.
     }
   };
@@ -43,8 +45,9 @@ public void update(byte[] keyBytes, Object value, MessageDigest messageDigest) {
    * @param key A unique package prefixed {@link String} that identifies this option (must be
    *            stable across builds, so {@link Class#getName()} should <em>not</em> be used).
    */
-  public static <T> Option<T> memory(String key) {
-    return new Option<>(key, null /*defaultValue*/, Option.<T>emptyUpdater());
+  @NonNull
+  public static <T> Option<T> memory(@NonNull String key) {
+    return new Option<>(key, null, Option.<T>emptyUpdater());
   }
 
   /**
@@ -54,7 +57,8 @@ public static <T> Option<T> memory(String key) {
    * @param key A unique package prefixed {@link String} that identifies this option (must be
    *            stable across builds, so {@link Class#getName()} should <em>not</em> be used).
    */
-  public static <T> Option<T> memory(String key, T defaultValue) {
+  @NonNull
+  public static <T> Option<T> memory(@NonNull String key, @NonNull T defaultValue) {
     return new Option<>(key, defaultValue, Option.<T>emptyUpdater());
   }
 
@@ -65,8 +69,10 @@ public static <T> Option<T> memory(String key, T defaultValue) {
    * @param key A unique package prefixed {@link String} that identifies this option (must be
    *            stable across builds, so {@link Class#getName()} should <em>not</em> be used).
    */
-  public static <T> Option<T> disk(String key, CacheKeyUpdater<T> cacheKeyUpdater) {
-    return new Option<>(key, null /*defaultValue*/, cacheKeyUpdater);
+  @NonNull
+  public static <T> Option<T> disk(@NonNull String key,
+      @NonNull CacheKeyUpdater<T> cacheKeyUpdater) {
+    return new Option<>(key, null, cacheKeyUpdater);
   }
 
   /**
@@ -77,11 +83,14 @@ public static <T> Option<T> disk(String key, CacheKeyUpdater<T> cacheKeyUpdater)
    * @param key A unique package prefixed {@link String} that identifies this option (must be
    *            stable across builds, so {@link Class#getName()} should <em>not</em> be used).
    */
-  public static <T> Option<T> disk(String key, T defaultValue, CacheKeyUpdater<T> cacheKeyUpdater) {
+  @NonNull
+  public static <T> Option<T> disk(@NonNull String key, @Nullable T defaultValue,
+      @NonNull CacheKeyUpdater<T> cacheKeyUpdater) {
     return new Option<>(key, defaultValue, cacheKeyUpdater);
   }
 
-  private Option(String key, T defaultValue, CacheKeyUpdater<T> cacheKeyUpdater) {
+  private Option(@NonNull String key, @Nullable T defaultValue,
+      @NonNull CacheKeyUpdater<T> cacheKeyUpdater) {
     this.key = Preconditions.checkNotEmpty(key);
     this.defaultValue = defaultValue;
     this.cacheKeyUpdater = Preconditions.checkNotNull(cacheKeyUpdater);
@@ -102,10 +111,11 @@ public T getDefaultValue() {
    * value using the {@link com.bumptech.glide.load.Option.CacheKeyUpdater} optionally provided in
    * the constructor.
    */
-  public void update(T value, MessageDigest messageDigest) {
+  public void update(@NonNull T value, @NonNull MessageDigest messageDigest) {
     cacheKeyUpdater.update(getKeyBytes(), value, messageDigest);
   }
 
+  @NonNull
   private byte[] getKeyBytes() {
     if (keyBytes == null) {
       keyBytes = key.getBytes(Key.CHARSET);
@@ -127,6 +137,7 @@ public int hashCode() {
     return key.hashCode();
   }
 
+  @NonNull
   @SuppressWarnings("unchecked")
   private static <T> CacheKeyUpdater<T> emptyUpdater() {
     return (CacheKeyUpdater<T>) EMPTY_UPDATER;
@@ -162,6 +173,6 @@ public interface CacheKeyUpdater<T> {
      * to a byte array using some stable mechanism and then call
      * {@link MessageDigest#update(byte[])} to update the given digest.
      */
-    void update(byte[] keyBytes, T value, MessageDigest messageDigest);
+    void update(@NonNull byte[] keyBytes, @NonNull T value, @NonNull MessageDigest messageDigest);
   }
 }
diff --git a/library/src/main/java/com/bumptech/glide/load/Options.java b/library/src/main/java/com/bumptech/glide/load/Options.java
index 5ca52c84b8..bf2685323e 100644
--- a/library/src/main/java/com/bumptech/glide/load/Options.java
+++ b/library/src/main/java/com/bumptech/glide/load/Options.java
@@ -1,6 +1,7 @@
 package com.bumptech.glide.load;
 
 import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
 import android.support.v4.util.ArrayMap;
 import android.support.v4.util.SimpleArrayMap;
 import java.security.MessageDigest;
@@ -11,17 +12,19 @@
 public final class Options implements Key {
   private final ArrayMap<Option<?>, Object> values = new ArrayMap<>();
 
-  public void putAll(Options other) {
+  public void putAll(@NonNull Options other) {
     values.putAll((SimpleArrayMap<Option<?>, Object>) other.values);
   }
 
-  public <T> Options set(Option<T> option, T value) {
+  @NonNull
+  public <T> Options set(@NonNull Option<T> option, @NonNull T value) {
     values.put(option, value);
     return this;
   }
 
+  @Nullable
   @SuppressWarnings("unchecked")
-  public <T> T get(Option<T> option) {
+  public <T> T get(@NonNull Option<T> option) {
     return values.containsKey(option) ? (T) values.get(option) : option.getDefaultValue();
   }
 
@@ -56,7 +59,8 @@ public String toString() {
   }
 
   @SuppressWarnings("unchecked")
-  private static <T> void updateDiskCacheKey(Option<T> option, Object value, MessageDigest md) {
+  private static <T> void updateDiskCacheKey(@NonNull Option<T> option, @NonNull Object value,
+      @NonNull MessageDigest md) {
     option.update((T) value, md);
   }
 }
diff --git a/library/src/main/java/com/bumptech/glide/load/ResourceEncoder.java b/library/src/main/java/com/bumptech/glide/load/ResourceEncoder.java
index c0f5f13bac..d179858451 100644
--- a/library/src/main/java/com/bumptech/glide/load/ResourceEncoder.java
+++ b/library/src/main/java/com/bumptech/glide/load/ResourceEncoder.java
@@ -11,5 +11,6 @@
  */
 public interface ResourceEncoder<T> extends Encoder<Resource<T>> {
   // specializing the generic arguments
+  @NonNull
   EncodeStrategy getEncodeStrategy(@NonNull Options options);
 }
diff --git a/library/src/main/java/com/bumptech/glide/load/Transformation.java b/library/src/main/java/com/bumptech/glide/load/Transformation.java
index 996a20cd1a..2e9ab29d96 100644
--- a/library/src/main/java/com/bumptech/glide/load/Transformation.java
+++ b/library/src/main/java/com/bumptech/glide/load/Transformation.java
@@ -65,18 +65,4 @@ public interface Transformation<T> extends Key {
   @NonNull
   Resource<T> transform(@NonNull Context context, @NonNull Resource<T> resource,
       int outWidth, int outHeight);
-
-  /**
-   * For caching to work correctly, implementations <em>must</em> implement this method and
-   * {@link #hashCode()}.
-   */
-  @Override
-  boolean equals(Object o);
-
-  /**
-   * For caching to work correctly, implementations <em>must</em> implement this method and
-   * {@link #equals(Object)}.
-   */
-  @Override
-  int hashCode();
 }
diff --git a/library/src/main/java/com/bumptech/glide/load/engine/DecodeJob.java b/library/src/main/java/com/bumptech/glide/load/engine/DecodeJob.java
index 35a35ce80f..3fe0bb3d5e 100644
--- a/library/src/main/java/com/bumptech/glide/load/engine/DecodeJob.java
+++ b/library/src/main/java/com/bumptech/glide/load/engine/DecodeJob.java
@@ -140,8 +140,8 @@ boolean willDecodeFromCache() {
   /**
    * Called when this object is no longer in use externally.
    *
-   * @param isRemovedFromQueue {@code true} if we've been removed from the queue and {@link #run}
-   *                           is neither in progress nor will ever be called again.
+   * @param isRemovedFromQueue {@code true} if we've been removed from the queue and {@link #run} is
+   *                           neither in progress nor will ever be called again.
    */
   void release(boolean isRemovedFromQueue) {
     if (releaseManager.release(isRemovedFromQueue)) {
@@ -259,7 +259,7 @@ public void run() {
   }
 
   private void runWrapped() {
-     switch (runReason) {
+    switch (runReason) {
       case INITIALIZE:
         stage = getNextStage(Stage.INITIALIZE);
         currentGenerator = getNextGenerator();
@@ -399,8 +399,8 @@ private void decodeFromRetrievedData() {
     if (Log.isLoggable(TAG, Log.VERBOSE)) {
       logWithTimeAndKey("Retrieved data", startFetchTime,
           "data: " + currentData
-          + ", cache key: " + currentSourceKey
-          + ", fetcher: " + currentFetcher);
+              + ", cache key: " + currentSourceKey
+              + ", fetcher: " + currentFetcher);
     }
     Resource<R> resource = null;
     try {
@@ -469,6 +469,7 @@ private <Data> Resource<R> decodeFromFetcher(Data data, DataSource dataSource)
     return runLoadPath(data, dataSource, path);
   }
 
+  @NonNull
   private Options getOptionsWithHardwareConfig(DataSource dataSource) {
     Options options = this.options;
     if (Build.VERSION.SDK_INT < Build.VERSION_CODES.O) {
@@ -517,7 +518,10 @@ public StateVerifier getVerifier() {
     return stateVerifier;
   }
 
-  @Synthetic <Z> Resource<Z> onResourceDecoded(DataSource dataSource, Resource<Z> decoded) {
+  @Synthetic
+  @NonNull
+  <Z> Resource<Z> onResourceDecoded(DataSource dataSource,
+      @NonNull Resource<Z> decoded) {
     @SuppressWarnings("unchecked")
     Class<Z> resourceSubClass = (Class<Z>) decoded.get().getClass();
     Transformation<Z> appliedTransformation = null;
@@ -585,8 +589,9 @@ private final class DecodeCallback<Z> implements DecodePath.DecodeCallback<Z> {
       this.dataSource = dataSource;
     }
 
+    @NonNull
     @Override
-    public Resource<Z> onResourceDecoded(Resource<Z> decoded) {
+    public Resource<Z> onResourceDecoded(@NonNull Resource<Z> decoded) {
       return DecodeJob.this.onResourceDecoded(dataSource, decoded);
     }
   }
@@ -629,8 +634,8 @@ private boolean isComplete(boolean isRemovedFromQueue) {
   }
 
   /**
-   * Allows transformed resources to be encoded after the transcoded result is already delivered
-   * to requestors.
+   * Allows transformed resources to be encoded after the transcoded result is already delivered to
+   * requestors.
    */
   private static class DeferredEncodeManager<Z> {
     private Key key;
diff --git a/library/src/main/java/com/bumptech/glide/load/engine/DecodePath.java b/library/src/main/java/com/bumptech/glide/load/engine/DecodePath.java
index b9e2704a79..919dc7584a 100644
--- a/library/src/main/java/com/bumptech/glide/load/engine/DecodePath.java
+++ b/library/src/main/java/com/bumptech/glide/load/engine/DecodePath.java
@@ -1,5 +1,6 @@
 package com.bumptech.glide.load.engine;
 
+import android.support.annotation.NonNull;
 import android.support.v4.util.Pools.Pool;
 import android.util.Log;
 import com.bumptech.glide.load.Options;
@@ -40,14 +41,15 @@ public DecodePath(Class<DataType> dataClass, Class<ResourceType> resourceClass,
   }
 
   public Resource<Transcode> decode(DataRewinder<DataType> rewinder, int width, int height,
-      Options options, DecodeCallback<ResourceType> callback) throws GlideException {
+      @NonNull Options options, DecodeCallback<ResourceType> callback) throws GlideException {
     Resource<ResourceType> decoded = decodeResource(rewinder, width, height, options);
     Resource<ResourceType> transformed = callback.onResourceDecoded(decoded);
     return transcoder.transcode(transformed, options);
   }
 
+  @NonNull
   private Resource<ResourceType> decodeResource(DataRewinder<DataType> rewinder, int width,
-      int height, Options options) throws GlideException {
+      int height, @NonNull Options options) throws GlideException {
     List<Throwable> exceptions = Preconditions.checkNotNull(listPool.acquire());
     try {
       return decodeResourceWithList(rewinder, width, height, options, exceptions);
@@ -56,8 +58,9 @@ private Resource<ResourceType> decodeResource(DataRewinder<DataType> rewinder, i
     }
   }
 
+  @NonNull
   private Resource<ResourceType> decodeResourceWithList(DataRewinder<DataType> rewinder, int width,
-      int height, Options options, List<Throwable> exceptions) throws GlideException {
+      int height, @NonNull Options options, List<Throwable> exceptions) throws GlideException {
     Resource<ResourceType> result = null;
     //noinspection ForLoopReplaceableByForEach to improve perf
     for (int i = 0, size = decoders.size(); i < size; i++) {
@@ -95,6 +98,7 @@ public String toString() {
   }
 
   interface DecodeCallback<ResourceType> {
-    Resource<ResourceType> onResourceDecoded(Resource<ResourceType> resource);
+    @NonNull
+    Resource<ResourceType> onResourceDecoded(@NonNull Resource<ResourceType> resource);
   }
 }
diff --git a/library/src/main/java/com/bumptech/glide/load/engine/LoadPath.java b/library/src/main/java/com/bumptech/glide/load/engine/LoadPath.java
index fd50d328a1..dca8f89529 100644
--- a/library/src/main/java/com/bumptech/glide/load/engine/LoadPath.java
+++ b/library/src/main/java/com/bumptech/glide/load/engine/LoadPath.java
@@ -1,5 +1,6 @@
 package com.bumptech.glide.load.engine;
 
+import android.support.annotation.NonNull;
 import android.support.v4.util.Pools.Pool;
 import com.bumptech.glide.load.Options;
 import com.bumptech.glide.load.data.DataRewinder;
@@ -35,7 +36,7 @@ public LoadPath(Class<Data> dataClass, Class<ResourceType> resourceClass,
         + resourceClass.getSimpleName() + "->" + transcodeClass.getSimpleName() + "}";
   }
 
-  public Resource<Transcode> load(DataRewinder<Data> rewinder, Options options, int width,
+  public Resource<Transcode> load(DataRewinder<Data> rewinder, @NonNull Options options, int width,
       int height, DecodePath.DecodeCallback<ResourceType> decodeCallback) throws GlideException {
     List<Throwable> throwables = Preconditions.checkNotNull(listPool.acquire());
     try {
@@ -45,7 +46,8 @@ public Resource<Transcode> load(DataRewinder<Data> rewinder, Options options, in
     }
   }
 
-  private Resource<Transcode> loadWithExceptionList(DataRewinder<Data> rewinder, Options options,
+  private Resource<Transcode> loadWithExceptionList(DataRewinder<Data> rewinder,
+      @NonNull Options options,
       int width, int height, DecodePath.DecodeCallback<ResourceType> decodeCallback,
       List<Throwable> exceptions) throws GlideException {
     Resource<Transcode> result = null;
diff --git a/library/src/main/java/com/bumptech/glide/load/engine/LockedResource.java b/library/src/main/java/com/bumptech/glide/load/engine/LockedResource.java
index c1c43ec6ea..594b264414 100644
--- a/library/src/main/java/com/bumptech/glide/load/engine/LockedResource.java
+++ b/library/src/main/java/com/bumptech/glide/load/engine/LockedResource.java
@@ -29,6 +29,7 @@ public LockedResource<?> create() {
   private boolean isRecycled;
 
   @SuppressWarnings("unchecked")
+  @NonNull
   static <Z> LockedResource<Z> obtain(Resource<Z> resource) {
     LockedResource<Z> result = Preconditions.checkNotNull((LockedResource<Z>) POOL.acquire());
     result.init(resource);
diff --git a/library/src/main/java/com/bumptech/glide/load/resource/SimpleResource.java b/library/src/main/java/com/bumptech/glide/load/resource/SimpleResource.java
index 1ee1ac609b..9b6c8e465c 100644
--- a/library/src/main/java/com/bumptech/glide/load/resource/SimpleResource.java
+++ b/library/src/main/java/com/bumptech/glide/load/resource/SimpleResource.java
@@ -15,7 +15,7 @@
 public class SimpleResource<T> implements Resource<T> {
   protected final T data;
 
-  public SimpleResource(T data) {
+  public SimpleResource(@NonNull T data) {
     this.data = Preconditions.checkNotNull(data);
   }
 
diff --git a/library/src/main/java/com/bumptech/glide/load/resource/UnitTransformation.java b/library/src/main/java/com/bumptech/glide/load/resource/UnitTransformation.java
index d5da9985ee..9602c25642 100644
--- a/library/src/main/java/com/bumptech/glide/load/resource/UnitTransformation.java
+++ b/library/src/main/java/com/bumptech/glide/load/resource/UnitTransformation.java
@@ -20,6 +20,7 @@ public final class UnitTransformation<T> implements Transformation<T> {
    * @param <T> The type of the resource to be transformed.
    */
   @SuppressWarnings("unchecked")
+  @NonNull
   public static <T> UnitTransformation<T> get() {
     return (UnitTransformation<T>) TRANSFORMATION;
   }
diff --git a/library/src/main/java/com/bumptech/glide/load/resource/bitmap/BitmapDrawableEncoder.java b/library/src/main/java/com/bumptech/glide/load/resource/bitmap/BitmapDrawableEncoder.java
index 656bdf66c5..a955d9d059 100644
--- a/library/src/main/java/com/bumptech/glide/load/resource/bitmap/BitmapDrawableEncoder.java
+++ b/library/src/main/java/com/bumptech/glide/load/resource/bitmap/BitmapDrawableEncoder.java
@@ -29,6 +29,7 @@ public boolean encode(@NonNull Resource<BitmapDrawable> data, @NonNull File file
     return encoder.encode(new BitmapResource(data.get().getBitmap(), bitmapPool), file, options);
   }
 
+  @NonNull
   @Override
   public EncodeStrategy getEncodeStrategy(@NonNull Options options) {
     return encoder.getEncodeStrategy(options);
diff --git a/library/src/main/java/com/bumptech/glide/load/resource/bitmap/BitmapDrawableTransformation.java b/library/src/main/java/com/bumptech/glide/load/resource/bitmap/BitmapDrawableTransformation.java
index b0dc28cb2c..a783e616c4 100644
--- a/library/src/main/java/com/bumptech/glide/load/resource/bitmap/BitmapDrawableTransformation.java
+++ b/library/src/main/java/com/bumptech/glide/load/resource/bitmap/BitmapDrawableTransformation.java
@@ -48,11 +48,11 @@ public BitmapDrawableTransformation(
     this(wrapped);
   }
 
+  @NonNull
   @Override
   public Resource<BitmapDrawable> transform(
-      Context context, Resource<BitmapDrawable> drawableResourceToTransform, int outWidth,
-      int outHeight) {
-
+      @NonNull Context context, @NonNull Resource<BitmapDrawable> drawableResourceToTransform,
+      int outWidth, int outHeight) {
     Resource<Drawable> toTransform = convertToDrawableResource(drawableResourceToTransform);
     Resource<Drawable> transformed = wrapped.transform(context, toTransform, outWidth, outHeight);
     return convertToBitmapDrawableResource(transformed);
diff --git a/library/src/main/java/com/bumptech/glide/load/resource/bitmap/BitmapEncoder.java b/library/src/main/java/com/bumptech/glide/load/resource/bitmap/BitmapEncoder.java
index 8de58d9a30..5c949e6e3e 100644
--- a/library/src/main/java/com/bumptech/glide/load/resource/bitmap/BitmapEncoder.java
+++ b/library/src/main/java/com/bumptech/glide/load/resource/bitmap/BitmapEncoder.java
@@ -125,6 +125,7 @@ private Bitmap.CompressFormat getFormat(Bitmap bitmap, Options options) {
     }
   }
 
+  @NonNull
   @Override
   public EncodeStrategy getEncodeStrategy(@NonNull Options options) {
     return EncodeStrategy.TRANSFORMED;
diff --git a/library/src/main/java/com/bumptech/glide/load/resource/bitmap/DefaultImageHeaderParser.java b/library/src/main/java/com/bumptech/glide/load/resource/bitmap/DefaultImageHeaderParser.java
index a2252613bc..a6e7c10cbb 100644
--- a/library/src/main/java/com/bumptech/glide/load/resource/bitmap/DefaultImageHeaderParser.java
+++ b/library/src/main/java/com/bumptech/glide/load/resource/bitmap/DefaultImageHeaderParser.java
@@ -6,6 +6,7 @@
 import static com.bumptech.glide.load.ImageHeaderParser.ImageType.PNG_A;
 import static com.bumptech.glide.load.ImageHeaderParser.ImageType.UNKNOWN;
 
+import android.support.annotation.NonNull;
 import android.util.Log;
 import com.bumptech.glide.load.ImageHeaderParser;
 import com.bumptech.glide.load.engine.bitmap_recycle.ArrayPool;
@@ -56,28 +57,33 @@ public final class DefaultImageHeaderParser implements ImageHeaderParser {
   private static final int WEBP_EXTENDED_ALPHA_FLAG = 1 << 4;
   private static final int WEBP_LOSSLESS_ALPHA_FLAG = 1 << 3;
 
+  @NonNull
   @Override
-  public ImageType getType(InputStream is) throws IOException {
+  public ImageType getType(@NonNull InputStream is) throws IOException {
     return getType(new StreamReader(Preconditions.checkNotNull(is)));
   }
 
+  @NonNull
   @Override
-  public ImageType getType(ByteBuffer byteBuffer) throws IOException {
+  public ImageType getType(@NonNull ByteBuffer byteBuffer) throws IOException {
     return getType(new ByteBufferReader(Preconditions.checkNotNull(byteBuffer)));
   }
 
   @Override
-  public int getOrientation(InputStream is, ArrayPool byteArrayPool) throws IOException {
+  public int getOrientation(@NonNull InputStream is, @NonNull ArrayPool byteArrayPool)
+      throws IOException {
     return getOrientation(new StreamReader(Preconditions.checkNotNull(is)),
         Preconditions.checkNotNull(byteArrayPool));
   }
 
   @Override
-  public int getOrientation(ByteBuffer byteBuffer, ArrayPool byteArrayPool) throws IOException {
+  public int getOrientation(@NonNull ByteBuffer byteBuffer, @NonNull ArrayPool byteArrayPool)
+      throws IOException {
     return getOrientation(new ByteBufferReader(Preconditions.checkNotNull(byteBuffer)),
         Preconditions.checkNotNull(byteArrayPool));
   }
 
+  @NonNull
   private ImageType getType(Reader reader) throws IOException {
     final int firstTwoBytes = reader.getUInt16();
 
@@ -232,13 +238,13 @@ private int moveToExifSegmentAndGetLength(Reader reader) throws IOException {
       if (segmentType != EXIF_SEGMENT_TYPE) {
         long skipped = reader.skip(segmentLength);
         if (skipped != segmentLength) {
-            if (Log.isLoggable(TAG, Log.DEBUG)) {
-                Log.d(TAG, "Unable to skip enough data"
-                    + ", type: " + segmentType
-                    + ", wanted to skip: " + segmentLength
-                    + ", but actually skipped: " + skipped);
-            }
-            return -1;
+          if (Log.isLoggable(TAG, Log.DEBUG)) {
+            Log.d(TAG, "Unable to skip enough data"
+                + ", type: " + segmentType
+                + ", wanted to skip: " + segmentLength
+                + ", but actually skipped: " + skipped);
+          }
+          return -1;
         }
       } else {
         return segmentLength;
@@ -389,24 +395,24 @@ private static final class ByteBufferReader implements Reader {
     }
 
     @Override
-    public int getUInt16() throws IOException {
+    public int getUInt16() {
       return (getByte() << 8 & 0xFF00) | (getByte() & 0xFF);
     }
 
     @Override
-    public short getUInt8() throws IOException {
+    public short getUInt8() {
       return (short) (getByte() & 0xFF);
     }
 
     @Override
-    public long skip(long total) throws IOException {
+    public long skip(long total) {
       int toSkip = (int) Math.min(byteBuffer.remaining(), total);
       byteBuffer.position(byteBuffer.position() + toSkip);
       return toSkip;
     }
 
     @Override
-    public int read(byte[] buffer, int byteCount) throws IOException {
+    public int read(byte[] buffer, int byteCount) {
       int toRead = Math.min(byteCount, byteBuffer.remaining());
       if (toRead == 0) {
         return -1;
@@ -416,7 +422,7 @@ public int read(byte[] buffer, int byteCount) throws IOException {
     }
 
     @Override
-    public int getByte() throws IOException {
+    public int getByte() {
       if (byteBuffer.remaining() < 1) {
         return -1;
       }
@@ -426,6 +432,7 @@ public int getByte() throws IOException {
 
   private static final class StreamReader implements Reader {
     private final InputStream is;
+
     // Motorola / big endian byte order.
     StreamReader(InputStream is) {
       this.is = is;
diff --git a/library/src/main/java/com/bumptech/glide/load/resource/bitmap/Downsampler.java b/library/src/main/java/com/bumptech/glide/load/resource/bitmap/Downsampler.java
index 5647f6dcc5..51e9be79ac 100644
--- a/library/src/main/java/com/bumptech/glide/load/resource/bitmap/Downsampler.java
+++ b/library/src/main/java/com/bumptech/glide/load/resource/bitmap/Downsampler.java
@@ -87,8 +87,7 @@ public final class Downsampler {
    * <p>This option is ignored unless we're on Android O+.
    */
   public static final Option<Boolean> ALLOW_HARDWARE_CONFIG =
-      Option.memory(
-          "com.bumtpech.glide.load.resource.bitmap.Downsampler.AllowHardwareDecode", null);
+      Option.memory("com.bumtpech.glide.load.resource.bitmap.Downsampler.AllowHardwareDecode");
 
   private static final String WBMP_MIME_TYPE = "image/vnd.wap.wbmp";
   private static final String ICO_MIME_TYPE = "image/x-ico";
diff --git a/library/src/main/java/com/bumptech/glide/load/resource/bitmap/LazyBitmapDrawableResource.java b/library/src/main/java/com/bumptech/glide/load/resource/bitmap/LazyBitmapDrawableResource.java
index ae2ef225dc..92855b5ba2 100644
--- a/library/src/main/java/com/bumptech/glide/load/resource/bitmap/LazyBitmapDrawableResource.java
+++ b/library/src/main/java/com/bumptech/glide/load/resource/bitmap/LazyBitmapDrawableResource.java
@@ -56,7 +56,8 @@ public static Resource<BitmapDrawable> obtain(
 
   }
 
-  private LazyBitmapDrawableResource(Resources resources, Resource<Bitmap> bitmapResource) {
+  private LazyBitmapDrawableResource(@NonNull Resources resources,
+      @NonNull Resource<Bitmap> bitmapResource) {
     this.resources = Preconditions.checkNotNull(resources);
     this.bitmapResource = Preconditions.checkNotNull(bitmapResource);
   }
diff --git a/library/src/main/java/com/bumptech/glide/load/resource/bitmap/RecyclableBufferedInputStream.java b/library/src/main/java/com/bumptech/glide/load/resource/bitmap/RecyclableBufferedInputStream.java
index aa21f9ce9b..c8139383f5 100644
--- a/library/src/main/java/com/bumptech/glide/load/resource/bitmap/RecyclableBufferedInputStream.java
+++ b/library/src/main/java/com/bumptech/glide/load/resource/bitmap/RecyclableBufferedInputStream.java
@@ -65,12 +65,12 @@ public class RecyclableBufferedInputStream extends FilterInputStream {
   private int pos;
   private final ArrayPool byteArrayPool;
 
-  public RecyclableBufferedInputStream(InputStream in, ArrayPool byteArrayPool) {
+  public RecyclableBufferedInputStream(@NonNull InputStream in, @NonNull ArrayPool byteArrayPool) {
     this(in, byteArrayPool, ArrayPool.STANDARD_BUFFER_SIZE_BYTES);
   }
 
   @VisibleForTesting
-  RecyclableBufferedInputStream(InputStream in, ArrayPool byteArrayPool,
+  RecyclableBufferedInputStream(@NonNull InputStream in, @NonNull ArrayPool byteArrayPool,
       int bufferSize) {
     super(in);
     this.byteArrayPool = byteArrayPool;
diff --git a/library/src/main/java/com/bumptech/glide/load/resource/bitmap/VideoDecoder.java b/library/src/main/java/com/bumptech/glide/load/resource/bitmap/VideoDecoder.java
index fb697b39bf..509e83e103 100644
--- a/library/src/main/java/com/bumptech/glide/load/resource/bitmap/VideoDecoder.java
+++ b/library/src/main/java/com/bumptech/glide/load/resource/bitmap/VideoDecoder.java
@@ -53,8 +53,10 @@ public class VideoDecoder<T> implements ResourceDecoder<T, Bitmap> {
       "com.bumptech.glide.load.resource.bitmap.VideoBitmapDecode.TargetFrame", DEFAULT_FRAME,
       new Option.CacheKeyUpdater<Long>() {
         private final ByteBuffer buffer = ByteBuffer.allocate(Long.SIZE / Byte.SIZE);
+
         @Override
-        public void update(byte[] keyBytes, Long value, MessageDigest messageDigest) {
+        public void update(@NonNull byte[] keyBytes, @NonNull Long value,
+            @NonNull MessageDigest messageDigest) {
           messageDigest.update(keyBytes);
           synchronized (buffer) {
             buffer.position(0);
@@ -78,8 +80,11 @@ public void update(byte[] keyBytes, Long value, MessageDigest messageDigest) {
       /*defaultValue=*/ MediaMetadataRetriever.OPTION_CLOSEST_SYNC,
       new Option.CacheKeyUpdater<Integer>() {
         private final ByteBuffer buffer = ByteBuffer.allocate(Integer.SIZE / Byte.SIZE);
+
         @Override
-        public void update(byte[] keyBytes, Integer value, MessageDigest messageDigest) {
+        public void update(@NonNull byte[] keyBytes, @NonNull Integer value,
+            @NonNull MessageDigest messageDigest) {
+          //noinspection ConstantConditions public API, people could have been doing it wrong
           if (value == null) {
             return;
           }
@@ -175,10 +180,10 @@ private static Bitmap decodeFrame(
     // Target.SIZE_ORIGINAL is not used and not using getScaledFrameAtTime ever would match the
     // behavior of Glide in all versions of Android prior to OMR1, it's probably fine for now.
     if (Build.VERSION.SDK_INT >= VERSION_CODES.O_MR1
-         && outWidth != Target.SIZE_ORIGINAL
-         && outHeight != Target.SIZE_ORIGINAL) {
-       return mediaMetadataRetriever.getScaledFrameAtTime(
-           frameTimeMicros, frameOption, outWidth, outHeight);
+        && outWidth != Target.SIZE_ORIGINAL
+        && outHeight != Target.SIZE_ORIGINAL) {
+      return mediaMetadataRetriever.getScaledFrameAtTime(
+          frameTimeMicros, frameOption, outWidth, outHeight);
     } else {
       return mediaMetadataRetriever.getFrameAtTime(frameTimeMicros, frameOption);
     }
diff --git a/library/src/main/java/com/bumptech/glide/load/resource/gif/GifDrawableEncoder.java b/library/src/main/java/com/bumptech/glide/load/resource/gif/GifDrawableEncoder.java
index 8bd26919dd..e73f713dcc 100644
--- a/library/src/main/java/com/bumptech/glide/load/resource/gif/GifDrawableEncoder.java
+++ b/library/src/main/java/com/bumptech/glide/load/resource/gif/GifDrawableEncoder.java
@@ -17,6 +17,7 @@
 public class GifDrawableEncoder implements ResourceEncoder<GifDrawable> {
   private static final String TAG = "GifEncoder";
 
+  @NonNull
   @Override
   public EncodeStrategy getEncodeStrategy(@NonNull Options options) {
     return EncodeStrategy.SOURCE;
diff --git a/library/src/main/java/com/bumptech/glide/load/resource/transcode/BitmapBytesTranscoder.java b/library/src/main/java/com/bumptech/glide/load/resource/transcode/BitmapBytesTranscoder.java
index 66f3f86e1c..9274b56ff4 100644
--- a/library/src/main/java/com/bumptech/glide/load/resource/transcode/BitmapBytesTranscoder.java
+++ b/library/src/main/java/com/bumptech/glide/load/resource/transcode/BitmapBytesTranscoder.java
@@ -1,6 +1,8 @@
 package com.bumptech.glide.load.resource.transcode;
 
 import android.graphics.Bitmap;
+import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
 import com.bumptech.glide.load.Options;
 import com.bumptech.glide.load.engine.Resource;
 import com.bumptech.glide.load.resource.bytes.BytesResource;
@@ -22,13 +24,15 @@ public BitmapBytesTranscoder() {
 
   // Public API.
   @SuppressWarnings("WeakerAccess")
-  public BitmapBytesTranscoder(Bitmap.CompressFormat compressFormat, int quality) {
+  public BitmapBytesTranscoder(@NonNull Bitmap.CompressFormat compressFormat, int quality) {
     this.compressFormat = compressFormat;
     this.quality = quality;
   }
 
+  @Nullable
   @Override
-  public Resource<byte[]> transcode(Resource<Bitmap> toTranscode, Options options) {
+  public Resource<byte[]> transcode(@NonNull Resource<Bitmap> toTranscode,
+      @NonNull Options options) {
     ByteArrayOutputStream os = new ByteArrayOutputStream();
     toTranscode.get().compress(compressFormat, quality, os);
     toTranscode.recycle();
diff --git a/library/src/main/java/com/bumptech/glide/load/resource/transcode/BitmapDrawableTranscoder.java b/library/src/main/java/com/bumptech/glide/load/resource/transcode/BitmapDrawableTranscoder.java
index a5a61ead99..b9dc68bb5e 100644
--- a/library/src/main/java/com/bumptech/glide/load/resource/transcode/BitmapDrawableTranscoder.java
+++ b/library/src/main/java/com/bumptech/glide/load/resource/transcode/BitmapDrawableTranscoder.java
@@ -5,6 +5,7 @@
 import android.graphics.Bitmap;
 import android.graphics.drawable.BitmapDrawable;
 import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
 import com.bumptech.glide.load.Options;
 import com.bumptech.glide.load.engine.Resource;
 import com.bumptech.glide.load.engine.bitmap_recycle.BitmapPool;
@@ -37,8 +38,10 @@ public BitmapDrawableTranscoder(@NonNull Resources resources) {
     this.resources = Preconditions.checkNotNull(resources);
   }
 
+  @Nullable
   @Override
-  public Resource<BitmapDrawable> transcode(Resource<Bitmap> toTranscode, Options options) {
+  public Resource<BitmapDrawable> transcode(@NonNull Resource<Bitmap> toTranscode,
+      @NonNull Options options) {
     return LazyBitmapDrawableResource.obtain(resources, toTranscode);
   }
 }
diff --git a/library/src/main/java/com/bumptech/glide/load/resource/transcode/DrawableBytesTranscoder.java b/library/src/main/java/com/bumptech/glide/load/resource/transcode/DrawableBytesTranscoder.java
index 59be855f36..a37e16ff6b 100644
--- a/library/src/main/java/com/bumptech/glide/load/resource/transcode/DrawableBytesTranscoder.java
+++ b/library/src/main/java/com/bumptech/glide/load/resource/transcode/DrawableBytesTranscoder.java
@@ -4,6 +4,7 @@
 import android.graphics.Bitmap;
 import android.graphics.drawable.BitmapDrawable;
 import android.graphics.drawable.Drawable;
+import android.support.annotation.NonNull;
 import android.support.annotation.Nullable;
 import com.bumptech.glide.load.Options;
 import com.bumptech.glide.load.engine.Resource;
@@ -15,17 +16,15 @@
  * Obtains {@code byte[]} from {@link BitmapDrawable}s by delegating to a
  * {@link ResourceTranscoder} for {@link Bitmap}s to {@code byte[]}s.
  */
-public final class DrawableBytesTranscoder
-    implements ResourceTranscoder<Drawable, byte[]> {
-
+public final class DrawableBytesTranscoder implements ResourceTranscoder<Drawable, byte[]> {
   private final BitmapPool bitmapPool;
   private final ResourceTranscoder<Bitmap, byte[]> bitmapBytesTranscoder;
   private final ResourceTranscoder<GifDrawable, byte[]> gifDrawableBytesTranscoder;
 
   public DrawableBytesTranscoder(
-      BitmapPool bitmapPool,
-      ResourceTranscoder<Bitmap, byte[]> bitmapBytesTranscoder,
-      ResourceTranscoder<GifDrawable, byte[]> gifDrawableBytesTranscoder) {
+      @NonNull BitmapPool bitmapPool,
+      @NonNull ResourceTranscoder<Bitmap, byte[]> bitmapBytesTranscoder,
+      @NonNull ResourceTranscoder<GifDrawable, byte[]> gifDrawableBytesTranscoder) {
     this.bitmapPool = bitmapPool;
     this.bitmapBytesTranscoder = bitmapBytesTranscoder;
     this.gifDrawableBytesTranscoder = gifDrawableBytesTranscoder;
@@ -33,7 +32,8 @@ public DrawableBytesTranscoder(
 
   @Nullable
   @Override
-  public Resource<byte[]> transcode(Resource<Drawable> toTranscode, Options options) {
+  public Resource<byte[]> transcode(@NonNull Resource<Drawable> toTranscode,
+      @NonNull Options options) {
     Drawable drawable = toTranscode.get();
     if (drawable instanceof BitmapDrawable) {
       return bitmapBytesTranscoder.transcode(
@@ -45,7 +45,8 @@ public Resource<byte[]> transcode(Resource<Drawable> toTranscode, Options option
   }
 
   @SuppressWarnings("unchecked")
-  private static Resource<GifDrawable> toGifDrawableResource(Resource<Drawable> resource) {
+  @NonNull
+  private static Resource<GifDrawable> toGifDrawableResource(@NonNull Resource<Drawable> resource) {
     return (Resource<GifDrawable>) (Resource<?>) resource;
   }
 }
diff --git a/library/src/main/java/com/bumptech/glide/load/resource/transcode/GifDrawableBytesTranscoder.java b/library/src/main/java/com/bumptech/glide/load/resource/transcode/GifDrawableBytesTranscoder.java
index 0bc3c12b31..69e82202d4 100644
--- a/library/src/main/java/com/bumptech/glide/load/resource/transcode/GifDrawableBytesTranscoder.java
+++ b/library/src/main/java/com/bumptech/glide/load/resource/transcode/GifDrawableBytesTranscoder.java
@@ -1,5 +1,7 @@
 package com.bumptech.glide.load.resource.transcode;
 
+import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
 import com.bumptech.glide.load.Options;
 import com.bumptech.glide.load.engine.Resource;
 import com.bumptech.glide.load.resource.bytes.BytesResource;
@@ -13,8 +15,10 @@
  * the GIF from the {@link com.bumptech.glide.load.resource.gif.GifDrawable}.
  */
 public class GifDrawableBytesTranscoder implements ResourceTranscoder<GifDrawable, byte[]> {
+  @Nullable
   @Override
-  public Resource<byte[]> transcode(Resource<GifDrawable> toTranscode, Options options) {
+  public Resource<byte[]> transcode(@NonNull Resource<GifDrawable> toTranscode,
+      @NonNull Options options) {
     GifDrawable gifData = toTranscode.get();
     ByteBuffer byteBuffer = gifData.getBuffer();
     return new BytesResource(ByteBufferUtil.toBytes(byteBuffer));
diff --git a/library/src/main/java/com/bumptech/glide/load/resource/transcode/ResourceTranscoder.java b/library/src/main/java/com/bumptech/glide/load/resource/transcode/ResourceTranscoder.java
index e84bd6b000..fbd4631bd3 100644
--- a/library/src/main/java/com/bumptech/glide/load/resource/transcode/ResourceTranscoder.java
+++ b/library/src/main/java/com/bumptech/glide/load/resource/transcode/ResourceTranscoder.java
@@ -1,5 +1,7 @@
 package com.bumptech.glide.load.resource.transcode;
 
+import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
 import com.bumptech.glide.load.Options;
 import com.bumptech.glide.load.engine.Resource;
 
@@ -16,5 +18,6 @@ public interface ResourceTranscoder<Z, R> {
    *
    * @param toTranscode The resource to transcode.
    */
-  Resource<R> transcode(Resource<Z> toTranscode, Options options);
+  @Nullable
+  Resource<R> transcode(@NonNull Resource<Z> toTranscode, @NonNull Options options);
 }
diff --git a/library/src/main/java/com/bumptech/glide/load/resource/transcode/UnitTranscoder.java b/library/src/main/java/com/bumptech/glide/load/resource/transcode/UnitTranscoder.java
index a52fb33b5d..45efdf5a1f 100644
--- a/library/src/main/java/com/bumptech/glide/load/resource/transcode/UnitTranscoder.java
+++ b/library/src/main/java/com/bumptech/glide/load/resource/transcode/UnitTranscoder.java
@@ -1,5 +1,7 @@
 package com.bumptech.glide.load.resource.transcode;
 
+import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
 import com.bumptech.glide.load.Options;
 import com.bumptech.glide.load.engine.Resource;
 
@@ -16,8 +18,9 @@ public static <Z> ResourceTranscoder<Z, Z> get() {
     return (ResourceTranscoder<Z, Z>) UNIT_TRANSCODER;
   }
 
+  @Nullable
   @Override
-  public Resource<Z> transcode(Resource<Z> toTranscode, Options options) {
+  public Resource<Z> transcode(@NonNull Resource<Z> toTranscode, @NonNull Options options) {
     return toTranscode;
   }
 }
diff --git a/library/test/src/test/java/com/bumptech/glide/load/OptionsTest.java b/library/test/src/test/java/com/bumptech/glide/load/OptionsTest.java
index eb45b43212..67ee5b1937 100644
--- a/library/test/src/test/java/com/bumptech/glide/load/OptionsTest.java
+++ b/library/test/src/test/java/com/bumptech/glide/load/OptionsTest.java
@@ -1,5 +1,6 @@
 package com.bumptech.glide.load;
 
+import android.support.annotation.NonNull;
 import com.bumptech.glide.load.Option.CacheKeyUpdater;
 import com.bumptech.glide.tests.KeyTester;
 import java.nio.ByteBuffer;
@@ -24,7 +25,8 @@ public void testEquals() {
 
     CacheKeyUpdater<Integer> updater = new CacheKeyUpdater<Integer>() {
       @Override
-      public void update(byte[] keyBytes, Integer value, MessageDigest messageDigest) {
+      public void update(@NonNull byte[] keyBytes, @NonNull Integer value,
+          @NonNull MessageDigest messageDigest) {
         messageDigest.update(keyBytes);
         messageDigest.update(ByteBuffer.allocate(4).putInt(value).array());
 
diff --git a/library/test/src/test/java/com/bumptech/glide/load/engine/EngineKeyTest.java b/library/test/src/test/java/com/bumptech/glide/load/engine/EngineKeyTest.java
index 78c47be66b..f18a302895 100644
--- a/library/test/src/test/java/com/bumptech/glide/load/engine/EngineKeyTest.java
+++ b/library/test/src/test/java/com/bumptech/glide/load/engine/EngineKeyTest.java
@@ -1,5 +1,6 @@
 package com.bumptech.glide.load.engine;
 
+import android.support.annotation.NonNull;
 import com.bumptech.glide.load.Key;
 import com.bumptech.glide.load.Option;
 import com.bumptech.glide.load.Option.CacheKeyUpdater;
@@ -55,7 +56,8 @@ public void testEqualsAndHashCode() {
     Options diskOptions = new Options();
     diskOptions.set(Option.disk("key", new CacheKeyUpdater<String>() {
       @Override
-      public void update(byte[] keyBytes, String value, MessageDigest messageDigest) {
+      public void update(@NonNull byte[] keyBytes, @NonNull String value,
+          @NonNull MessageDigest messageDigest) {
         messageDigest.update(keyBytes);
         messageDigest.update(value.getBytes(Key.CHARSET));
 
diff --git a/library/test/src/test/java/com/bumptech/glide/load/engine/ResourceCacheKeyTest.java b/library/test/src/test/java/com/bumptech/glide/load/engine/ResourceCacheKeyTest.java
index f95935d852..bcefcbb1a9 100644
--- a/library/test/src/test/java/com/bumptech/glide/load/engine/ResourceCacheKeyTest.java
+++ b/library/test/src/test/java/com/bumptech/glide/load/engine/ResourceCacheKeyTest.java
@@ -3,6 +3,7 @@
 import static org.mockito.Matchers.any;
 import static org.mockito.Mockito.doAnswer;
 
+import android.support.annotation.NonNull;
 import com.bumptech.glide.load.Key;
 import com.bumptech.glide.load.Option;
 import com.bumptech.glide.load.Option.CacheKeyUpdater;
@@ -13,7 +14,6 @@
 import com.bumptech.glide.tests.KeyTester;
 import com.bumptech.glide.tests.Util;
 import java.security.MessageDigest;
-import java.security.NoSuchAlgorithmException;
 import java.util.Arrays;
 import org.junit.Before;
 import org.junit.Rule;
@@ -45,21 +45,21 @@ public void setUp() {
   }
 
   @Test
-  public void testEqualsAndHashCode() throws NoSuchAlgorithmException {
+  public void testEqualsAndHashCode() {
     Options memoryOptions = new Options();
     memoryOptions.set(Option.memory("key", new Object()), new Object());
 
     Options diskOptions = new Options();
     diskOptions.set(Option.disk("key", new CacheKeyUpdater<String>() {
       @Override
-      public void update(byte[] keyBytes, String value, MessageDigest messageDigest) {
+      public void update(@NonNull byte[] keyBytes, @NonNull String value,
+          @NonNull MessageDigest messageDigest) {
         messageDigest.update(keyBytes);
         messageDigest.update(value.getBytes(Key.CHARSET));
 
       }
     }), "value");
 
-
     for (int i = 0; i < 20; i++) {
       byte[] array = new byte[9];
       Arrays.fill(array, (byte) 2);
diff --git a/samples/svg/src/main/java/com/bumptech/glide/samples/svg/SvgDrawableTranscoder.java b/samples/svg/src/main/java/com/bumptech/glide/samples/svg/SvgDrawableTranscoder.java
index 6b6b2ba1d9..a3fd80abfd 100644
--- a/samples/svg/src/main/java/com/bumptech/glide/samples/svg/SvgDrawableTranscoder.java
+++ b/samples/svg/src/main/java/com/bumptech/glide/samples/svg/SvgDrawableTranscoder.java
@@ -2,6 +2,8 @@
 
 import android.graphics.Picture;
 import android.graphics.drawable.PictureDrawable;
+import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
 import com.bumptech.glide.load.Options;
 import com.bumptech.glide.load.engine.Resource;
 import com.bumptech.glide.load.resource.SimpleResource;
@@ -13,12 +15,13 @@
  * ({@link Picture}).
  */
 public class SvgDrawableTranscoder implements ResourceTranscoder<SVG, PictureDrawable> {
+  @Nullable
   @Override
-  public Resource<PictureDrawable> transcode(Resource<SVG> toTranscode, Options options) {
+  public Resource<PictureDrawable> transcode(@NonNull Resource<SVG> toTranscode,
+      @NonNull Options options) {
     SVG svg = toTranscode.get();
     Picture picture = svg.renderToPicture();
     PictureDrawable drawable = new PictureDrawable(picture);
     return new SimpleResource<>(drawable);
   }
 }
-