Remove nullable annotation configuration in fix serialization. (#621)

Following GH-517 If `serializeFixMetadata` is active, `NullAway` will serialize suggested type changes (currently just adding `@Nullable`). In the `FixSerializationConfig` file we can set a custom annotation that `NullAway` will use in the output serializations. 

However, this process can be simplified by just asking `NullAway` to serialize type change locations with a default annotation name, any tool processing this output can use their own preferred annotation.

After this PR the following entity will be removed from the config `.xml` file:
```xml
<annotation>
       <nonnull> ... </nonnull>
       <nullable> ... </nullable>
</annotation
```
And a sample out below:
```
Field bar of Foo, ASSIGN_FIELD_NULLABLE, @nullable
```

Will be changed to simply:
```
Field bar of Foo, ASSIGN_FIELD_NULLABLE, nullable
```

nullaway/src/main/java/com/uber/nullaway/fixserialization/FixSerializationConfig.java

@@ -23,7 +23,7 @@
 package com.uber.nullaway.fixserialization;
 
 import com.google.common.base.Preconditions;
-import com.uber.nullaway.fixserialization.qual.AnnotationConfig;
+import com.uber.nullaway.fixserialization.out.SuggestedNullableFixInfo;
 import java.io.IOException;
 import java.nio.file.Files;
 import java.nio.file.Paths;
@@ -41,9 +41,9 @@ public class FixSerializationConfig {
    * If enabled, the corresponding output file will be cleared and for all reported errors, NullAway
    * will serialize information and suggest type changes to resolve them, in case these errors could
    * be fixed by adding a {@code @Nullable} annotation. These type change suggestions are in form of
-   * {@link com.uber.nullaway.fixserialization.out.SuggestedFixInfo} instances and will be
-   * serialized at output directory. If deactivated, no {@code SuggestedFixInfo} will be created and
-   * the output file will remain untouched.
+   * {@link SuggestedNullableFixInfo} instances and will be serialized at output directory. If
+   * deactivated, no {@code SuggestedFixInfo} will be created and the output file will remain
+   * untouched.
    */
   public final boolean suggestEnabled;
   /**
@@ -62,16 +62,13 @@ public class FixSerializationConfig {
   /** The directory where all files generated/read by Fix Serialization package resides. */
   @Nullable public final String outputDirectory;
 
-  public final AnnotationConfig annotationConfig;
-
   @Nullable private final Serializer serializer;
 
   /** Default Constructor, all features are disabled with this config. */
   public FixSerializationConfig() {
     suggestEnabled = false;
     suggestEnclosing = false;
     fieldInitInfoEnabled = false;
-    annotationConfig = new AnnotationConfig();
     outputDirectory = null;
     serializer = null;
   }
@@ -80,13 +77,11 @@ public FixSerializationConfig(
       boolean suggestEnabled,
       boolean suggestEnclosing,
       boolean fieldInitInfoEnabled,
-      AnnotationConfig annotationConfig,
-      String outputDirectory) {
+      @Nullable String outputDirectory) {
     this.suggestEnabled = suggestEnabled;
     this.suggestEnclosing = suggestEnclosing;
     this.fieldInitInfoEnabled = fieldInitInfoEnabled;
     this.outputDirectory = outputDirectory;
-    this.annotationConfig = annotationConfig;
     serializer = new Serializer(this);
   }
 
@@ -124,13 +119,6 @@ public FixSerializationConfig(String configFilePath) {
         XMLUtil.getValueFromAttribute(
                 document, "/serialization/fieldInitInfo", "active", Boolean.class)
             .orElse(false);
-    String nullableAnnot =
-        XMLUtil.getValueFromTag(document, "/serialization/annotation/nullable", String.class)
-            .orElse("javax.annotation.Nullable");
-    String nonnullAnnot =
-        XMLUtil.getValueFromTag(document, "/serialization/annotation/nonnull", String.class)
-            .orElse("javax.annotation.Nonnull");
-    this.annotationConfig = new AnnotationConfig(nullableAnnot, nonnullAnnot);
     serializer = new Serializer(this);
   }
 
@@ -145,16 +133,12 @@ public static class Builder {
     private boolean suggestEnabled;
     private boolean suggestEnclosing;
     private boolean fieldInitInfo;
-    private String nullable;
-    private String nonnull;
     @Nullable private String outputDir;
 
     public Builder() {
       suggestEnabled = false;
       suggestEnclosing = false;
       fieldInitInfo = false;
-      nullable = "javax.annotation.Nullable";
-      nonnull = "javax.annotation.Nonnull";
     }
 
     public Builder setSuggest(boolean value, boolean withEnclosing) {
@@ -163,12 +147,6 @@ public Builder setSuggest(boolean value, boolean withEnclosing) {
       return this;
     }
 
-    public Builder setAnnotations(String nullable, String nonnull) {
-      this.nullable = nullable;
-      this.nonnull = nonnull;
-      return this;
-    }
-
     public Builder setFieldInitInfo(boolean enabled) {
       this.fieldInitInfo = enabled;
       return this;
@@ -193,12 +171,7 @@ public FixSerializationConfig build() {
       if (outputDir == null) {
         throw new IllegalStateException("did not set mandatory output directory");
       }
-      return new FixSerializationConfig(
-          suggestEnabled,
-          suggestEnclosing,
-          fieldInitInfo,
-          new AnnotationConfig(nullable, nonnull),
-          outputDir);
+      return new FixSerializationConfig(suggestEnabled, suggestEnclosing, fieldInitInfo, outputDir);
     }
   }
 }

nullaway/src/main/java/com/uber/nullaway/fixserialization/SerializationService.java

@@ -33,7 +33,7 @@
 import com.uber.nullaway.Nullness;
 import com.uber.nullaway.fixserialization.location.FixLocation;
 import com.uber.nullaway.fixserialization.out.ErrorInfo;
-import com.uber.nullaway.fixserialization.out.SuggestedFixInfo;
+import com.uber.nullaway.fixserialization.out.SuggestedNullableFixInfo;
 
 /** A facade class to interact with fix serialization package. */
 public class SerializationService {
@@ -65,12 +65,13 @@ public static void serializeFixSuggestion(
       return;
     }
     FixLocation location = FixLocation.createFixLocationFromSymbol(target);
-    SuggestedFixInfo suggestedFixInfo =
-        buildFixMetadata(config, state.getPath(), errorMessage, location);
+    SuggestedNullableFixInfo suggestedNullableFixInfo =
+        buildFixMetadata(state.getPath(), errorMessage, location);
     Serializer serializer = serializationConfig.getSerializer();
     Preconditions.checkNotNull(
         serializer, "Serializer shouldn't be null at this point, error in configuration setting!");
-    serializer.serializeSuggestedFixInfo(suggestedFixInfo, serializationConfig.suggestEnclosing);
+    serializer.serializeSuggestedFixInfo(
+        suggestedNullableFixInfo, serializationConfig.suggestEnclosing);
   }
 
   /**
@@ -88,10 +89,12 @@ public static void serializeReportingError(
     serializer.serializeErrorInfo(new ErrorInfo(state.getPath(), errorMessage));
   }
 
-  /** Builds the {@link SuggestedFixInfo} instance based on the {@link ErrorMessage} type. */
-  private static SuggestedFixInfo buildFixMetadata(
-      Config config, TreePath path, ErrorMessage errorMessage, FixLocation location) {
-    SuggestedFixInfo suggestedFixInfo;
+  /**
+   * Builds the {@link SuggestedNullableFixInfo} instance based on the {@link ErrorMessage} type.
+   */
+  private static SuggestedNullableFixInfo buildFixMetadata(
+      TreePath path, ErrorMessage errorMessage, FixLocation location) {
+    SuggestedNullableFixInfo suggestedNullableFixInfo;
     switch (errorMessage.getMessageType()) {
       case RETURN_NULLABLE:
       case WRONG_OVERRIDE_RETURN:
@@ -100,17 +103,12 @@ private static SuggestedFixInfo buildFixMetadata(
       case FIELD_NO_INIT:
       case ASSIGN_FIELD_NULLABLE:
       case METHOD_NO_INIT:
-        suggestedFixInfo =
-            new SuggestedFixInfo(
-                path,
-                location,
-                errorMessage,
-                config.getSerializationConfig().annotationConfig.getNullable());
+        suggestedNullableFixInfo = new SuggestedNullableFixInfo(path, location, errorMessage);
         break;
       default:
         throw new IllegalStateException(
             "Cannot suggest a type to resolve error of type: " + errorMessage.getMessageType());
     }
-    return suggestedFixInfo;
+    return suggestedNullableFixInfo;
   }
 }

nullaway/src/main/java/com/uber/nullaway/fixserialization/Serializer.java

@@ -25,7 +25,7 @@
 import com.uber.nullaway.ErrorMessage;
 import com.uber.nullaway.fixserialization.out.ErrorInfo;
 import com.uber.nullaway.fixserialization.out.FieldInitializationInfo;
-import com.uber.nullaway.fixserialization.out.SuggestedFixInfo;
+import com.uber.nullaway.fixserialization.out.SuggestedNullableFixInfo;
 import java.io.FileOutputStream;
 import java.io.IOException;
 import java.io.OutputStream;
@@ -55,16 +55,17 @@ public Serializer(FixSerializationConfig config) {
   }
 
   /**
-   * Appends the string representation of the {@link SuggestedFixInfo}.
+   * Appends the string representation of the {@link SuggestedNullableFixInfo}.
    *
-   * @param suggestedFixInfo SuggestedFixInfo object.
+   * @param suggestedNullableFixInfo SuggestedFixInfo object.
    * @param enclosing Flag to control if enclosing method and class should be included.
    */
-  public void serializeSuggestedFixInfo(SuggestedFixInfo suggestedFixInfo, boolean enclosing) {
+  public void serializeSuggestedFixInfo(
+      SuggestedNullableFixInfo suggestedNullableFixInfo, boolean enclosing) {
     if (enclosing) {
-      suggestedFixInfo.initEnclosing();
+      suggestedNullableFixInfo.initEnclosing();
     }
-    appendToFile(suggestedFixInfo.tabSeparatedToString(), suggestedFixesOutputPath);
+    appendToFile(suggestedNullableFixInfo.tabSeparatedToString(), suggestedFixesOutputPath);
   }
 
   /**
@@ -102,7 +103,7 @@ private void initializeOutputFiles(FixSerializationConfig config) {
     try {
       Files.createDirectories(Paths.get(config.outputDirectory));
       if (config.suggestEnabled) {
-        initializeFile(suggestedFixesOutputPath, SuggestedFixInfo.header());
+        initializeFile(suggestedFixesOutputPath, SuggestedNullableFixInfo.header());
       }
       if (config.fieldInitInfoEnabled) {
         initializeFile(fieldInitializationOutputPath, FieldInitializationInfo.header());

nullaway/src/main/java/com/uber/nullaway/fixserialization/XMLUtil.java

@@ -121,16 +121,6 @@ public static void writeInXMLFormat(FixSerializationConfig config, String path)
       fieldInitInfoEnabled.setAttribute("active", String.valueOf(config.fieldInitInfoEnabled));
       rootElement.appendChild(fieldInitInfoEnabled);
 
-      // Annotations
-      Element annots = doc.createElement("annotation");
-      Element nonnull = doc.createElement("nonnull");
-      nonnull.setTextContent(config.annotationConfig.getNonNull().getFullName());
-      Element nullable = doc.createElement("nullable");
-      nullable.setTextContent(config.annotationConfig.getNullable().getFullName());
-      annots.appendChild(nullable);
-      annots.appendChild(nonnull);
-      rootElement.appendChild(annots);
-
       // Output dir
       Element outputDir = doc.createElement("path");
       outputDir.setTextContent(config.outputDirectory);

nullaway/src/main/java/com/uber/nullaway/fixserialization/out/SuggestedFixInfo.java → nullaway/src/main/java/com/uber/nullaway/fixserialization/out/SuggestedNullableFixInfo.java

@@ -26,64 +26,56 @@
 import com.sun.source.util.TreePath;
 import com.uber.nullaway.ErrorMessage;
 import com.uber.nullaway.fixserialization.location.FixLocation;
-import com.uber.nullaway.fixserialization.qual.AnnotationConfig;
 import java.util.Objects;
 
-/** Stores information suggesting a type change of an element in source code. */
-public class SuggestedFixInfo {
+/** Stores information suggesting adding @Nullable on an element in source code. */
+public class SuggestedNullableFixInfo {
 
   /** FixLocation of the target element in source code. */
   private final FixLocation fixLocation;
   /** Error which will be resolved by this type change. */
   private final ErrorMessage errorMessage;
-  /** Suggested annotation. */
-  private final AnnotationConfig.Annotation annotation;
 
   private final ClassAndMethodInfo classAndMethodInfo;
 
-  public SuggestedFixInfo(
-      TreePath path,
-      FixLocation fixLocation,
-      ErrorMessage errorMessage,
-      AnnotationConfig.Annotation annotation) {
+  public SuggestedNullableFixInfo(
+      TreePath path, FixLocation fixLocation, ErrorMessage errorMessage) {
     this.classAndMethodInfo = new ClassAndMethodInfo(path);
     this.fixLocation = fixLocation;
     this.errorMessage = errorMessage;
-    this.annotation = annotation;
   }
 
   @Override
   public boolean equals(Object o) {
     if (this == o) {
       return true;
     }
-    if (!(o instanceof SuggestedFixInfo)) {
+    if (!(o instanceof SuggestedNullableFixInfo)) {
       return false;
     }
-    SuggestedFixInfo suggestedFixInfo = (SuggestedFixInfo) o;
-    return Objects.equals(fixLocation, suggestedFixInfo.fixLocation)
-        && Objects.equals(annotation, suggestedFixInfo.annotation)
+    SuggestedNullableFixInfo suggestedNullableFixInfo = (SuggestedNullableFixInfo) o;
+    return Objects.equals(fixLocation, suggestedNullableFixInfo.fixLocation)
         && Objects.equals(
             errorMessage.getMessageType().toString(),
-            suggestedFixInfo.errorMessage.getMessageType().toString());
+            suggestedNullableFixInfo.errorMessage.getMessageType().toString());
   }
 
   @Override
   public int hashCode() {
-    return Objects.hash(fixLocation, annotation, errorMessage.getMessageType().toString());
+    return Objects.hash(fixLocation, errorMessage.getMessageType().toString());
   }
 
   /**
    * returns string representation of content of an object.
    *
-   * @return string representation of contents of an object in a line seperated by tabs.
+   * @return string representation of contents of an object in a line separated by tabs.
    */
   public String tabSeparatedToString() {
     return fixLocation.tabSeparatedToString()
         + '\t'
         + errorMessage.getMessageType().toString()
         + '\t'
-        + annotation
+        + "nullable"
         + '\t'
         + (classAndMethodInfo.getClazz() == null
             ? "null"
@@ -100,8 +92,8 @@ public void initEnclosing() {
   }
 
   /**
-   * Creates header of an output file containing all {@link SuggestedFixInfo} written in string
-   * which values are separated by tabs.
+   * Creates header of an output file containing all {@link SuggestedNullableFixInfo} written in
+   * string which values are separated by tabs.
    *
    * @return string representation of the header separated by tabs.
    */