diff --git a/composer.json b/composer.json
index 3a8450814e3..b9abb362327 100644
--- a/composer.json
+++ b/composer.json
@@ -22,16 +22,17 @@
     },
     "require-dev": {
         "cweagans/composer-patches": "^1.7",
-        "php-parallel-lint/php-parallel-lint": "^1.3",
-        "phpstan/extension-installer": "^1.3",
-        "phpstan/phpstan": "^1.10",
+        "php-parallel-lint/php-parallel-lint": "^1.4",
+        "phpstan/extension-installer": "^1.4",
+        "phpstan/phpstan": "^1.12",
         "phpunit/phpunit": "^10.5",
-        "rector/rector": "^0.19",
+        "rector/rector": "^1.2",
         "shipmonk/composer-dependency-analyser": "^1.7",
-        "symplify/easy-coding-standard": "^12.1",
+        "symplify/easy-coding-standard": "^12.3",
         "symplify/phpstan-extensions": "^11.4",
         "symplify/vendor-patches": "^11.3",
-        "tomasvotruba/class-leak": "^0.2.6"
+        "tomasvotruba/class-leak": "^1.0",
+        "tomasvotruba/unused-public": "^1.0"
     },
     "autoload": {
         "psr-4": {
diff --git a/phpstan.neon b/phpstan.neon
index ff40832de50..d69db5710df 100644
--- a/phpstan.neon
+++ b/phpstan.neon
@@ -11,6 +11,11 @@ parameters:
         - '*/Source/*'
         - '*/Fixture/*'
 
+    unused_public:
+        constants: true
+        properties: true
+        methods: true
+
     ignoreErrors:
         -
             message: '#Parameter \#1 \$commandName of method Symfony\\Component\\Console\\Application\:\:setDefaultCommand\(\) expects string, string\|null given#'
diff --git a/src/ConfigLoader.php b/src/ConfigLoader.php
index adca633f1e2..7e25288353d 100644
--- a/src/ConfigLoader.php
+++ b/src/ConfigLoader.php
@@ -21,7 +21,6 @@
 use Symplify\ConfigTransformer\DependencyInjection\Loader\SkippingPhpFileLoader;
 use Symplify\ConfigTransformer\Enum\Format;
 use Symplify\ConfigTransformer\Exception\NotImplementedYetException;
-use Symplify\ConfigTransformer\ValueObject\ContainerBuilderAndFileContent;
 
 final class ConfigLoader
 {
@@ -44,7 +43,7 @@ public function __construct(
 
     public function createAndLoadContainerBuilderFromFileInfo(
         SplFileInfo $fileInfo,
-    ): ContainerBuilderAndFileContent {
+    ): string {
         $containerBuilder = new ContainerBuilder();
 
         $delegatingLoader = $this->createLoaderBySuffix($containerBuilder, $fileInfo->getExtension());
@@ -85,7 +84,7 @@ public function createAndLoadContainerBuilderFromFileInfo(
             // usefull in gradual upgrade of configs
         }
 
-        return new ContainerBuilderAndFileContent($containerBuilder, $content);
+        return $content;
     }
 
     private function createLoaderBySuffix(ContainerBuilder $containerBuilder, string $suffix): DelegatingLoader
diff --git a/src/Converter/ConfigFormatConverter.php b/src/Converter/ConfigFormatConverter.php
index 97baf432103..ab5c550a55a 100644
--- a/src/Converter/ConfigFormatConverter.php
+++ b/src/Converter/ConfigFormatConverter.php
@@ -23,13 +23,12 @@ public function convert(SplFileInfo $fileInfo): string
     {
         $this->currentFilePathProvider->setFilePath($fileInfo->getRealPath());
 
-        $containerBuilderAndFileContent = $this->configLoader->createAndLoadContainerBuilderFromFileInfo(
+        $dumpedContainerContent = $this->configLoader->createAndLoadContainerBuilderFromFileInfo(
             $fileInfo
         );
 
         if (in_array($fileInfo->getExtension(), [Format::YAML, Format::YML], true)) {
-            $dumpedYaml = $containerBuilderAndFileContent->getFileContent();
-            return $this->yamlToPhpConverter->convert($dumpedYaml, $fileInfo->getRealPath());
+            return $this->yamlToPhpConverter->convert($dumpedContainerContent, $fileInfo->getRealPath());
         }
 
         $message = sprintf('Suffix "%s" is not support yet', $fileInfo->getExtension());
diff --git a/src/Reflection/PrivatesAccessor.php b/src/Reflection/PrivatesAccessor.php
index 49a9287d904..6da44f7d945 100644
--- a/src/Reflection/PrivatesAccessor.php
+++ b/src/Reflection/PrivatesAccessor.php
@@ -8,15 +8,6 @@
 
 final class PrivatesAccessor
 {
-    // read private property
-    public static function readPrivateProperty(object $object, string $propertyName): mixed
-    {
-        $reflectionProperty = new ReflectionProperty($object, $propertyName);
-        $reflectionProperty->setAccessible(true);
-
-        return $reflectionProperty->getValue($object);
-    }
-
     // write private property
     public static function writePrivateProperty(object $object, string $propertyName, mixed $value): void
     {
diff --git a/src/ValueObject/ContainerBuilderAndFileContent.php b/src/ValueObject/ContainerBuilderAndFileContent.php
deleted file mode 100644
index 6e90c5f2102..00000000000
--- a/src/ValueObject/ContainerBuilderAndFileContent.php
+++ /dev/null
@@ -1,26 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace Symplify\ConfigTransformer\ValueObject;
-
-use Symfony\Component\DependencyInjection\ContainerBuilder;
-
-final class ContainerBuilderAndFileContent
-{
-    public function __construct(
-        private readonly ContainerBuilder $containerBuilder,
-        private readonly string $fileContent
-    ) {
-    }
-
-    public function getContainerBuilder(): ContainerBuilder
-    {
-        return $this->containerBuilder;
-    }
-
-    public function getFileContent(): string
-    {
-        return $this->fileContent;
-    }
-}
diff --git a/tests/Helper/FixtureFinder.php b/tests/Helper/FixtureFinder.php
index 172080a3f96..19d56a091a0 100644
--- a/tests/Helper/FixtureFinder.php
+++ b/tests/Helper/FixtureFinder.php
@@ -11,6 +11,7 @@
 final class FixtureFinder
 {
     /**
+     * @api used in tests
      * @return Iterator<array<int, SplFileInfo>>
      */
     public static function yieldDirectory(string $directory, string $suffix = '*.php.inc'): Iterator
diff --git a/tests/Helper/FixtureSplitter.php b/tests/Helper/FixtureSplitter.php
index 00e22eb8658..a98be153d35 100644
--- a/tests/Helper/FixtureSplitter.php
+++ b/tests/Helper/FixtureSplitter.php
@@ -10,6 +10,9 @@
 use Symplify\ConfigTransformer\Tests\Helper\ValueObject\InputAndExpected;
 use Symplify\ConfigTransformer\Tests\Helper\ValueObject\InputFileInfoAndExpectedFileInfo;
 
+/**
+ * @api used in tests
+ */
 final class FixtureSplitter
 {
     /**
diff --git a/tests/Helper/FixtureUpdater.php b/tests/Helper/FixtureUpdater.php
index c47a2c7580d..61853a329cc 100644
--- a/tests/Helper/FixtureUpdater.php
+++ b/tests/Helper/FixtureUpdater.php
@@ -7,6 +7,9 @@
 use Nette\Utils\FileSystem;
 use Symfony\Component\Finder\SplFileInfo;
 
+/**
+ * @api used in tests
+ */
 final class FixtureUpdater
 {
     public static function updateFixtureContent(
diff --git a/tests/Helper/ValueObject/InputFileInfoAndExpectedFileInfo.php b/tests/Helper/ValueObject/InputFileInfoAndExpectedFileInfo.php
index 43d2e8ae007..8dee0ae270b 100644
--- a/tests/Helper/ValueObject/InputFileInfoAndExpectedFileInfo.php
+++ b/tests/Helper/ValueObject/InputFileInfoAndExpectedFileInfo.php
@@ -6,6 +6,9 @@
 
 use Symfony\Component\Finder\SplFileInfo;
 
+/**
+ * @api used in tests
+ */
 final class InputFileInfoAndExpectedFileInfo
 {
     public function __construct(
@@ -19,18 +22,8 @@ public function getInputFileInfo(): SplFileInfo
         return $this->inputFileInfo;
     }
 
-    public function getExpectedFileInfo(): SplFileInfo
-    {
-        return $this->expectedFileInfo;
-    }
-
     public function getExpectedFileContent(): string
     {
         return $this->expectedFileInfo->getContents();
     }
-
-    public function getExpectedFileInfoRealPath(): string
-    {
-        return $this->expectedFileInfo->getRealPath();
-    }
 }