[MRESOLVER-309] Do not kill the build when unkown remote layout (#233)

In case remote repository defines unsupported layout, filter should
just let it pass (as resolver will gracefully fail with it anyway),
while throwing RuntimeException caused abruptly stopped build.

---

https://issues.apache.org/jira/browse/MRESOLVER-309

Author: cstamas

maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/filter/PrefixesRemoteRepositoryFilterSource.java

@@ -112,7 +112,9 @@ public RemoteRepositoryFilter getRemoteRepositoryFilter( RepositorySystemSession
     }
 
     /**
-     * Caches layout instances for remote repository.
+     * Caches layout instances for remote repository. In case of unknown layout it returns {@code null}.
+     *
+     * @return the layout instance of {@code null} if layout not supported.
      */
     private RepositoryLayout cacheLayout( RepositorySystemSession session, RemoteRepository remoteRepository )
     {
@@ -124,7 +126,7 @@ private RepositoryLayout cacheLayout( RepositorySystemSession session, RemoteRep
             }
             catch ( NoRepositoryLayoutException e )
             {
-                throw new RuntimeException( e );
+                return null;
             }
         } );
     }
@@ -196,15 +198,25 @@ private PrefixesFilter( RepositorySystemSession session, Path basedir )
         @Override
         public Result acceptArtifact( RemoteRepository remoteRepository, Artifact artifact )
         {
+            RepositoryLayout repositoryLayout = cacheLayout( session, remoteRepository );
+            if ( repositoryLayout == null )
+            {
+                return new SimpleResult( true, "Unsupported layout: " + remoteRepository );
+            }
             return acceptPrefix( remoteRepository,
-                    cacheLayout( session, remoteRepository ).getLocation( artifact, false ).getPath() );
+                    repositoryLayout.getLocation( artifact, false ).getPath() );
         }
 
         @Override
         public Result acceptMetadata( RemoteRepository remoteRepository, Metadata metadata )
         {
+            RepositoryLayout repositoryLayout = cacheLayout( session, remoteRepository );
+            if ( repositoryLayout == null )
+            {
+                return new SimpleResult( true, "Unsupported layout: " + remoteRepository );
+            }
             return acceptPrefix( remoteRepository,
-                    cacheLayout( session, remoteRepository ).getLocation( metadata, false ).getPath() );
+                    repositoryLayout.getLocation( metadata, false ).getPath() );
         }
 
         private Result acceptPrefix( RemoteRepository remoteRepository, String path )