[MNG-8180] Back out from failing the build (#1642)

Just warn for now, we cannot go from builds-ok w/
3.9.8 to fails-the-build in 3.9.9. Warning
can raise awareness, and this pattern is bad as
it is, but users now become aware that they may
have rogue plugin.xml (just like maven-compat had).

The original bug is fixed (Maven deploys unrelated metadata).

Same change is to be ported to master as well.

---

https://issues.apache.org/jira/browse/MNG-8180

maven-resolver-provider/src/main/java/org/apache/maven/repository/internal/PluginsMetadataGenerator.java

@@ -42,6 +42,8 @@
 import org.eclipse.aether.installation.InstallRequest;
 import org.eclipse.aether.metadata.Metadata;
 import org.eclipse.aether.util.ConfigUtils;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 /**
  * Maven G level metadata generator.
@@ -51,6 +53,8 @@
 class PluginsMetadataGenerator implements MetadataGenerator {
     private static final String PLUGIN_DESCRIPTOR_LOCATION = "META-INF/maven/plugin.xml";
 
+    private final Logger logger = LoggerFactory.getLogger(getClass());
+
     private final Map<Object, PluginsMetadata> processedPlugins;
 
     private final Date timestamp;
@@ -142,20 +146,20 @@ private PluginInfo extractPluginInfo(Artifact artifact) {
                                 // here groupId and artifactId cannot be null
                                 return new PluginInfo(groupId, artifactId, goalPrefix, name);
                             } else {
-                                throw new InvalidArtifactPluginMetadataException(
-                                        "Artifact " + artifact.getGroupId() + ":"
-                                                + artifact.getArtifactId()
-                                                + " JAR (to be installed/deployed) contains Maven Plugin metadata for plugin "
-                                                + groupId + ":" + artifactId + "; coordinates are conflicting. "
-                                                + "Most probably your JAR contains rogue Maven Plugin metadata, "
-                                                + "possible causes may be: shaded in Maven Plugin or some rogue resource)");
+                                logger.warn(
+                                        "Artifact {}:{}"
+                                                + " JAR (about to be installed/deployed) contains Maven Plugin metadata for"
+                                                + " conflicting coordinates: {}:{}."
+                                                + " Your JAR contains rogue Maven Plugin metadata."
+                                                + " Possible causes may be: shaded into this JAR some Maven Plugin or some rogue resource.",
+                                        artifact.getGroupId(),
+                                        artifact.getArtifactId(),
+                                        groupId,
+                                        artifactId);
                             }
                         }
                     }
                 } catch (Exception e) {
-                    if (e instanceof InvalidArtifactPluginMetadataException) {
-                        throw (InvalidArtifactPluginMetadataException) e;
-                    }
                     // here we can have: IO. ZIP or Plexus Conf Ex: but we should not interfere with user intent
                 }
             }
@@ -170,10 +174,4 @@ private static String mayGetChild(Xpp3Dom node, String child) {
         }
         return null;
     }
-
-    public static final class InvalidArtifactPluginMetadataException extends IllegalArgumentException {
-        InvalidArtifactPluginMetadataException(String s) {
-            super(s);
-        }
-    }
 }

maven-resolver-provider/src/test/java/org/apache/maven/repository/internal/RepositorySystemTest.java

@@ -18,19 +18,15 @@
  */
 package org.apache.maven.repository.internal;
 
-import java.nio.file.Files;
 import java.util.Arrays;
 import java.util.List;
 
-import org.eclipse.aether.DefaultRepositorySystemSession;
 import org.eclipse.aether.artifact.Artifact;
 import org.eclipse.aether.artifact.DefaultArtifact;
 import org.eclipse.aether.collection.CollectRequest;
 import org.eclipse.aether.collection.CollectResult;
 import org.eclipse.aether.graph.Dependency;
 import org.eclipse.aether.graph.DependencyNode;
-import org.eclipse.aether.installation.InstallRequest;
-import org.eclipse.aether.repository.LocalRepository;
 import org.eclipse.aether.resolution.ArtifactDescriptorRequest;
 import org.eclipse.aether.resolution.ArtifactDescriptorResult;
 import org.eclipse.aether.resolution.ArtifactRequest;
@@ -197,29 +193,4 @@ public void testNewLocalRepositoryManager() throws Exception {
     public void testNewSyncContext() throws Exception {
         // SyncContext newSyncContext( RepositorySystemSession session, boolean shared );
     }
-
-    public void testRoguePlugin() throws Exception {
-        Artifact artifact = new DefaultArtifact("ut.simple:rogue-plugin:1.0");
-
-        ArtifactRequest artifactRequest = new ArtifactRequest();
-        artifactRequest.setArtifact(artifact);
-        artifactRequest.addRepository(newTestRepository());
-
-        ArtifactResult artifactResult = system.resolveArtifact(session, artifactRequest);
-        checkArtifactResult(artifactResult, "rogue-plugin-1.0.jar");
-
-        InstallRequest installRequest = new InstallRequest();
-        installRequest.addArtifact(artifactResult.getArtifact());
-
-        DefaultRepositorySystemSession loc = new DefaultRepositorySystemSession(session);
-        loc.setLocalRepositoryManager(system.newLocalRepositoryManager(
-                session, new LocalRepository(Files.createTempDirectory("local").toFile())));
-        try {
-            system.install(loc, installRequest);
-            fail("install should fail");
-        } catch (Exception e) {
-            assertTrue(e instanceof PluginsMetadataGenerator.InvalidArtifactPluginMetadataException);
-            assertTrue(e.getMessage().contains("coordinates are conflicting"));
-        }
-    }
 }