Improvements for ManifestResourceTransformer

api/shadow.api

@@ -450,17 +450,23 @@ public class com/github/jengelman/gradle/plugins/shadow/transformers/ManifestApp
 }
 
 public class com/github/jengelman/gradle/plugins/shadow/transformers/ManifestResourceTransformer : com/github/jengelman/gradle/plugins/shadow/transformers/ResourceTransformer {
+	public static final field Companion Lcom/github/jengelman/gradle/plugins/shadow/transformers/ManifestResourceTransformer$Companion;
+	public static final field NULL Ljava/lang/Object;
 	public fun <init> (Lorg/gradle/api/model/ObjectFactory;)V
 	public fun attributes (Ljava/util/Map;)V
 	public fun canTransformResource (Lorg/gradle/api/file/FileTreeElement;)Z
 	public fun getMainClass ()Lorg/gradle/api/provider/Property;
 	public fun getManifestEntries ()Lorg/gradle/api/provider/MapProperty;
 	public final fun getObjectFactory ()Lorg/gradle/api/model/ObjectFactory;
+	public fun getRelocateAttributes ()Lorg/gradle/api/provider/SetProperty;
 	public fun hasTransformedResource ()Z
 	public fun modifyOutputStream (Lorg/apache/tools/zip/ZipOutputStream;Z)V
 	public fun transform (Lcom/github/jengelman/gradle/plugins/shadow/transformers/TransformerContext;)V
 }
 
+public final class com/github/jengelman/gradle/plugins/shadow/transformers/ManifestResourceTransformer$Companion {
+}
+
 public class com/github/jengelman/gradle/plugins/shadow/transformers/MergeLicenseResourceTransformer : com/github/jengelman/gradle/plugins/shadow/transformers/PatternFilterableResourceTransformer {
 	public fun <init> (Lorg/gradle/api/model/ObjectFactory;)V
 	public fun <init> (Lorg/gradle/api/model/ObjectFactory;Lorg/gradle/api/tasks/util/PatternSet;)V

docs/changes/README.md

@@ -7,6 +7,9 @@
 
 - Allow configuring the final R8 configuration file with `R8Spec.configurationFile`. ([#2133](https://github.com/GradleUp/shadow/pull/2133))
 - Add `ProGuardFilesResourceTransformer` to merge R8/ProGuard rule files. ([#2196](https://github.com/GradleUp/shadow/pull/2196))
+- Improvements for `ManifestResourceTransformer`. ([#2200](https://github.com/GradleUp/shadow/pull/2200))
+  - Support removing manifest attributes using `NULL`.
+  - Support manifest header relocation via configurable `relocateAttributes` property.
 
 ### Changed
 
@@ -37,6 +40,8 @@
   Use `ShadowJar.exclude` or `ShadowJar.from` instead. The classes will be removed in Shadow 10.
 - Deprecate `TransformerContext.Builder`. ([#2184](https://github.com/GradleUp/shadow/pull/2184))  
   Use `TransformerContext` constructor instead. The Builder API will be removed in Shadow 10.
+- Deprecate `ManifestResourceTransformer.attributes(Map)`. ([#2200](https://github.com/GradleUp/shadow/pull/2200))  
+  Calling `manifestEntries` instead. The method will be removed in Shadow 10.
 
 ## [9.6.1](https://github.com/GradleUp/shadow/releases/tag/9.6.1) - 2026-07-22
 

src/functionalTest/kotlin/com/github/jengelman/gradle/plugins/shadow/transformers/TransformersTest.kt

@@ -2,10 +2,10 @@ package com.github.jengelman.gradle.plugins.shadow.transformers
 
 import assertk.all
 import assertk.assertThat
-import assertk.assertions.contains
 import assertk.assertions.isEqualTo
 import assertk.assertions.isNotEqualTo
 import assertk.assertions.isNotNull
+import assertk.assertions.isNull
 import com.github.jengelman.gradle.plugins.shadow.internal.mainClassAttributeKey
 import com.github.jengelman.gradle.plugins.shadow.testkit.containsOnly
 import com.github.jengelman.gradle.plugins.shadow.testkit.getContent
@@ -79,6 +79,35 @@ class TransformersTest : BaseTransformerTest() {
     }
   }
 
+  @Test
+  fun manifestResourceTransformerRemoveAttributes() {
+    writeClass()
+    projectScript.appendText(
+      """
+      |$jarTask {
+      |  manifest {
+      |    attributes 'Header-To-Remove-1': 'Value1', 'Header-To-Keep': 'Value2'
+      |  }
+      |}
+      |${transform<ManifestResourceTransformer>(
+        transformerBlock =
+          """
+          |manifestEntries.put('Header-To-Remove-1', ${ManifestResourceTransformer::class.java.name}.NULL)
+          """
+            .trimMargin()
+      )}
+      """
+        .trimMargin()
+    )
+
+    runWithSuccess(shadowJarPath)
+
+    commonAssertions {
+      assertThat(getValue("Header-To-Remove-1")).isNull()
+      assertThat(getValue("Header-To-Keep")).isEqualTo("Value2")
+    }
+  }
+
   @Test // #427
   fun mergeLog4j2PluginCacheFiles() {
     val content = requireResourceAsPath(PLUGIN_CACHE_FILE).readText()

src/main/kotlin/com/github/jengelman/gradle/plugins/shadow/internal/Relocators.kt

@@ -5,8 +5,15 @@ import com.github.jengelman.gradle.plugins.shadow.relocation.relocateClass
 import com.github.jengelman.gradle.plugins.shadow.relocation.relocatePath
 import java.util.regex.Pattern
 
+/**
+ * Matches Java class names, package wildcards (e.g. `com.foo.**`), single-segment packages, and
+ * inner classes (`com.foo.Bar$Inner`).
+ */
+internal val classNamePattern: Regex =
+  """(?<![a-zA-Z0-9_$.])([a-zA-Z_$][a-zA-Z0-9_$]*(?:\.[a-zA-Z0-9_$*?]+)*)""".toRegex()
+
 /** https://docs.oracle.com/javase/specs/jvms/se8/html/jvms-4.html */
-private val classPattern: Pattern = Pattern.compile("([\\[()BCDFIJSZ]*)?L([^;]+);?")
+private val typeDescriptorPattern = Pattern.compile("([\\[()BCDFIJSZ]*)?L([^;]+);?")
 
 internal fun Set<Relocator>.mapName(
   name: String,
@@ -30,7 +37,7 @@ private fun Set<Relocator>.realMap(name: String, mapLiterals: Boolean): String {
   var prefix = ""
   var suffix = ""
 
-  val matcher = classPattern.matcher(newName)
+  val matcher = typeDescriptorPattern.matcher(newName)
   if (matcher.matches()) {
     prefix = matcher.group(1) + "L"
     suffix = ""

src/main/kotlin/com/github/jengelman/gradle/plugins/shadow/transformers/ManifestResourceTransformer.kt

@@ -1,10 +1,14 @@
 package com.github.jengelman.gradle.plugins.shadow.transformers
 
 import com.github.jengelman.gradle.plugins.shadow.internal.checkDupStrategy
+import com.github.jengelman.gradle.plugins.shadow.internal.classNamePattern
 import com.github.jengelman.gradle.plugins.shadow.internal.mapProperty
 import com.github.jengelman.gradle.plugins.shadow.internal.property
+import com.github.jengelman.gradle.plugins.shadow.internal.setProperty
 import com.github.jengelman.gradle.plugins.shadow.internal.writeEntry
+import com.github.jengelman.gradle.plugins.shadow.relocation.relocateClass
 import java.io.IOException
+import java.io.Serializable
 import java.util.jar.Attributes.Name as JarAttributeName
 import java.util.jar.JarFile.MANIFEST_NAME
 import java.util.jar.Manifest
@@ -15,6 +19,7 @@ import org.gradle.api.logging.Logging
 import org.gradle.api.model.ObjectFactory
 import org.gradle.api.provider.MapProperty
 import org.gradle.api.provider.Property
+import org.gradle.api.provider.SetProperty
 import org.gradle.api.tasks.Input
 
 /**
@@ -37,8 +42,17 @@ constructor(final override val objectFactory: ObjectFactory) : ResourceTransform
 
   @get:Input public open val mainClass: Property<String> = objectFactory.property("")
 
+  /**
+   * Additional manifest entries to add to or remove from `MANIFEST.MF`.
+   *
+   * Setting an entry's value to [NULL] removes the corresponding attribute from the manifest.
+   */
   @get:Input public open val manifestEntries: MapProperty<String, Any> = objectFactory.mapProperty()
 
+  @get:Input
+  public open val relocateAttributes: SetProperty<String> =
+    objectFactory.setProperty(DEFAULT_RELOCATE_ATTRIBUTES)
+
   override fun canTransformResource(element: FileTreeElement): Boolean {
     return MANIFEST_NAME.equals(element.path, ignoreCase = true).also { flag ->
       checkDupStrategy(flag, element)
@@ -51,7 +65,21 @@ constructor(final override val objectFactory: ObjectFactory) : ResourceTransform
     // passed in with the processing so we cannot tell what artifact is being processed.
     if (!manifestDiscovered) {
       try {
-        manifest = Manifest(context.inputStream)
+        val loadedManifest = Manifest(context.inputStream)
+        if (context.relocators.isNotEmpty()) {
+          val attributes = loadedManifest.mainAttributes
+          for (attribute in relocateAttributes.get()) {
+            val attributeValue = attributes.getValue(attribute)
+            if (attributeValue != null) {
+              val newValue =
+                classNamePattern.replace(attributeValue) { matchResult ->
+                  context.relocators.relocateClass(matchResult.value)
+                }
+              attributes.putValue(attribute, newValue)
+            }
+          }
+        }
+        manifest = loadedManifest
         manifestDiscovered = true
       } catch (e: IOException) {
         logger.warn("Failed to read MANIFEST.MF", e)
@@ -71,22 +99,49 @@ constructor(final override val objectFactory: ObjectFactory) : ResourceTransform
     mainClass.get().takeIf(CharSequence::isNotEmpty)?.let {
       attributes[JarAttributeName.MAIN_CLASS] = it
     }
-    manifestEntries.get().forEach { (key, value) -> attributes.putValue(key, value.toString()) }
+    manifestEntries.get().forEach { (key, value) ->
+      if (value == NULL) {
+        attributes.remove(JarAttributeName(key))
+      } else {
+        attributes.putValue(key, value.toString())
+      }
+    }
 
     os.writeEntry(MANIFEST_NAME, preserveFileTimestamps) {
       manifest!!.write(this)
     }
   }
 
+  /**
+   * Adds the given attributes to [manifestEntries].
+   *
+   * If a value is `null`, it will be mapped to [NULL] to remove the attribute from the manifest.
+   */
+  @Deprecated(
+    "Use manifestEntries instead. This method will be removed in Shadow 10.",
+    replaceWith = ReplaceWith("manifestEntries.putAll(attributes)"),
+  )
   public open fun attributes(attributes: Map<String, *>) {
     attributes.forEach { (key, value) ->
-      if (value != null) {
-        manifestEntries.put(key, value)
-      }
+      manifestEntries.put(key, value ?: NULL)
     }
   }
 
-  private companion object {
+  public companion object {
+    private val DEFAULT_RELOCATE_ATTRIBUTES =
+      setOf("Export-Package", "Import-Package", "Provide-Capability", "Require-Capability")
+
     private val logger = Logging.getLogger(ManifestResourceTransformer::class.java)
+
+    /**
+     * A sentinel object used in [manifestEntries] or [attributes] to indicate that the specified
+     * manifest attribute should be removed from the merged `MANIFEST.MF`.
+     */
+    @JvmField
+    public val NULL: Any =
+      object : Serializable {
+        @Suppress("unused") // For JavaIoSerializableObjectMustHaveReadResolve.
+        private fun readResolve(): Any = NULL
+      }
   }
 }

src/main/kotlin/com/github/jengelman/gradle/plugins/shadow/transformers/ProGuardFilesResourceTransformer.kt

@@ -1,6 +1,7 @@
 package com.github.jengelman.gradle.plugins.shadow.transformers
 
 import com.github.jengelman.gradle.plugins.shadow.internal.checkDupStrategy
+import com.github.jengelman.gradle.plugins.shadow.internal.classNamePattern
 import com.github.jengelman.gradle.plugins.shadow.internal.writeEntry
 import com.github.jengelman.gradle.plugins.shadow.relocation.Relocator
 import com.github.jengelman.gradle.plugins.shadow.relocation.relocateClass
@@ -50,18 +51,11 @@ constructor(patternSet: PatternSet = PatternSet().include("META-INF/proguard/**"
   }
 
   internal companion object {
-    /**
-     * Matches Java class names, fully qualified class names, package wildcards (e.g. `com.foo.**`),
-     * and inner classes (`com.foo.Bar$Inner`).
-     */
-    private val CLASS_PATTERN =
-      """(?<![a-zA-Z0-9_$.])([a-zA-Z_$][a-zA-Z0-9_$]*(?:\.[a-zA-Z0-9_$*?]+)+)""".toRegex()
-
     fun Iterable<Relocator>.relocateRuleLine(line: String): String {
       return when {
         line.isBlank() || line.trimStart().startsWith("#") -> line
         else ->
-          CLASS_PATTERN.replace(line) { matchResult ->
+          classNamePattern.replace(line) { matchResult ->
             relocateClass(matchResult.value)
           }
       }

src/test/kotlin/com/github/jengelman/gradle/plugins/shadow/transformers/ManifestAppenderTransformerTest.kt

@@ -4,6 +4,7 @@ import assertk.assertThat
 import assertk.assertions.isEqualTo
 import assertk.assertions.isFalse
 import assertk.assertions.isTrue
+import com.github.jengelman.gradle.plugins.shadow.testkit.crlfEolString
 import com.github.jengelman.gradle.plugins.shadow.testkit.getContent
 import java.util.jar.JarFile.MANIFEST_NAME
 import org.junit.jupiter.api.Test
@@ -53,7 +54,7 @@ class ManifestAppenderTransformerTest : BaseTransformerTest<ManifestAppenderTran
           |
           |"""
             .trimMargin()
-            .replace("\n", "\r\n")
+            .crlfEolString
         )
     }