MSHADE-373: allow to specify optional target for resource transformers.

src/main/java/org/apache/maven/plugins/shade/mojo/ShadeMojo.java

@@ -458,31 +458,33 @@ public void execute()
 
             List<ResourceTransformer> resourceTransformers = getResourceTransformers();
 
-            ShadeRequest shadeRequest = shadeRequest( artifacts, outputJar, filters, relocators, resourceTransformers );
+            ShadeRequest shadeRequest = shadeRequest( "jar", artifacts, outputJar, filters, relocators,
+                    resourceTransformers );
 
             shader.shade( shadeRequest );
 
             if ( createSourcesJar )
             {
                 ShadeRequest shadeSourcesRequest =
-                    createShadeSourcesRequest( sourceArtifacts, sourcesJar, filters, relocators, resourceTransformers );
+                    createShadeSourcesRequest( "sources-jar", sourceArtifacts, sourcesJar, filters, relocators,
+                            resourceTransformers );
 
                 shader.shade( shadeSourcesRequest );
             }
 
             if ( shadeTestJar )
             {
                 ShadeRequest shadeTestRequest =
-                    shadeRequest( testArtifacts, testJar, filters, relocators, resourceTransformers );
+                    shadeRequest( "test-jar", testArtifacts, testJar, filters, relocators, resourceTransformers );
 
                 shader.shade( shadeTestRequest );
             }
 
             if ( createTestSourcesJar )
             {
                 ShadeRequest shadeTestSourcesRequest =
-                    createShadeSourcesRequest( testSourceArtifacts, testSourcesJar, filters, relocators,
-                        resourceTransformers );
+                    createShadeSourcesRequest( "test-sources-jar", testSourceArtifacts, testSourcesJar, filters,
+                        relocators, resourceTransformers );
 
                 shader.shade( shadeTestSourcesRequest );
             }
@@ -621,24 +623,24 @@ private void createErrorOutput()
         getLog().error( "- You removed the configuration of the maven-jar-plugin that produces the main artifact." );
     }
 
-    private ShadeRequest shadeRequest( Set<File> artifacts, File outputJar, List<Filter> filters,
+    private ShadeRequest shadeRequest( String shade, Set<File> artifacts, File outputJar, List<Filter> filters,
                                        List<Relocator> relocators, List<ResourceTransformer> resourceTransformers )
     {
         ShadeRequest shadeRequest = new ShadeRequest();
         shadeRequest.setJars( artifacts );
         shadeRequest.setUberJar( outputJar );
         shadeRequest.setFilters( filters );
         shadeRequest.setRelocators( relocators );
-        shadeRequest.setResourceTransformers( resourceTransformers );
+        shadeRequest.setResourceTransformers( toResourceTransformers( shade, resourceTransformers ) );
         return shadeRequest;
     }
 
-    private ShadeRequest createShadeSourcesRequest( Set<File> testArtifacts, File testJar, List<Filter> filters,
-                                                    List<Relocator> relocators,
+    private ShadeRequest createShadeSourcesRequest( String shade, Set<File> testArtifacts, File testJar,
+                                                    List<Filter> filters, List<Relocator> relocators,
                                                     List<ResourceTransformer> resourceTransformers )
     {
         ShadeRequest shadeSourcesRequest =
-            shadeRequest( testArtifacts, testJar, filters, relocators, resourceTransformers );
+            shadeRequest( shade, testArtifacts, testJar, filters, relocators, resourceTransformers );
         shadeSourcesRequest.setShadeSourcesContent( shadeSourcesContent );
         return shadeSourcesRequest;
     }
@@ -1314,4 +1316,18 @@ public boolean updateExcludesInDeps( MavenProject project, List<Dependency> depe
             session.getProjectBuildingRequest().setProject( original );
         }
     }
+
+    private List<ResourceTransformer> toResourceTransformers(
+            String shade, List<ResourceTransformer> resourceTransformers )
+    {
+         List<ResourceTransformer> forShade = new ArrayList<ResourceTransformer>();
+         for ( ResourceTransformer transformer : resourceTransformers )
+         {
+             if ( transformer.isForShade( shade ) )
+             {
+                 forShade.add( transformer );
+             }
+         }
+         return forShade;
+    }
 }

src/main/java/org/apache/maven/plugins/shade/resource/AbstractCompatibilityTransformer.java

@@ -29,6 +29,7 @@
  * An abstract class to implement once the old non-reproducible ResourceTransformer API.
  */
 abstract class AbstractCompatibilityTransformer
+    extends AbstractResourceTransformer
     implements ReproducibleResourceTransformer
 {
     public final void processResource( String resource, InputStream is, List<Relocator> relocators )

src/main/java/org/apache/maven/plugins/shade/resource/AbstractResourceTransformer.java

@@ -0,0 +1,41 @@
+package org.apache.maven.plugins.shade.resource;
+
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+import java.util.List;
+
+/**
+ * An abstract resource transformer implementing the eligible shades.
+ */
+public abstract class AbstractResourceTransformer implements ResourceTransformer
+{
+
+    private List<String> shades;
+
+    public final void setForShade( List<String> shades )
+    {
+        this.shades = shades;
+    }
+
+    public final boolean isForShade( String shade )
+    {
+        return shades == null || shades.isEmpty() || shades.contains( shade );
+    }
+}

src/main/java/org/apache/maven/plugins/shade/resource/ResourceTransformer.java

@@ -46,4 +46,13 @@ void processResource( String resource, InputStream is, List<Relocator> relocator
 
     void modifyOutputStream( JarOutputStream os )
         throws IOException;
+
+    /**
+     * The shades to apply this transformer to or no shades if no filter is applied.
+     *
+     * @param shades {@code jar}, {@code test-jar}, {@code sources-jar} or {@code test-sources-jar}.
+     */
+    void setForShade( List<String> shades );
+
+    boolean isForShade( String target );
 }

src/main/java/org/apache/maven/plugins/shade/resource/properties/PropertiesTransformer.java

@@ -32,6 +32,7 @@
 import java.util.jar.JarOutputStream;
 
 import org.apache.maven.plugins.shade.relocation.Relocator;
+import org.apache.maven.plugins.shade.resource.AbstractResourceTransformer;
 import org.apache.maven.plugins.shade.resource.ReproducibleResourceTransformer;
 import org.apache.maven.plugins.shade.resource.properties.io.NoCloseOutputStream;
 import org.apache.maven.plugins.shade.resource.properties.io.SkipPropertiesDateLineWriter;
@@ -42,6 +43,7 @@
  * @since 3.2.2
  */
 public class PropertiesTransformer
+    extends AbstractResourceTransformer
     implements ReproducibleResourceTransformer
 {
     private String resource;

src/test/java/org/apache/maven/plugins/shade/custom/CustomReproducibleResourceTransformer.java

@@ -25,13 +25,15 @@
 import java.util.jar.JarOutputStream;
 
 import org.apache.maven.plugins.shade.relocation.Relocator;
+import org.apache.maven.plugins.shade.resource.AbstractResourceTransformer;
 import org.apache.maven.plugins.shade.resource.ReproducibleResourceTransformer;
 
 /**
  * Custom ReproducibleResourceTransformer for MSHADE-363_old-plugin IT, to check that it can be run with
  * an older maven-shade-plugin that does not contain the ReproducibleResourceTransformer interface.
  */
 public class CustomReproducibleResourceTransformer
+    extends AbstractResourceTransformer
     implements ReproducibleResourceTransformer
 {
     @Override