Add get/setParentContainer to the configuration, and use it in

the embedder.

If the classrealm that's passed in has a parent realm, 
then only the resources from the realm are scanned (getRealmResources).
This was done to re-use components from parent realms.

However, when embedding maven within another plexus container,
providing a new dummy classworld with the current classloader
as the parent, no components will be found. Since there's no 
parent container, it won't be checked for components.

So, allowing a parent realm to be set in classworlds also
requires a parent container to be set, so that when no components
are found (since they're present in the parent container),
there is a parent container available to delegate lookups to.


git-svn-id: https://svn.apache.org/repos/asf/maven/components/trunk@563173 13f79535-47bb-0310-9956-ffa450edef68

maven-embedder/src/main/java/org/apache/maven/embedder/Configuration.java

@@ -18,6 +18,7 @@
  * under the License.
  */
 
+import org.codehaus.plexus.PlexusContainer;
 import org.codehaus.plexus.classworlds.ClassWorld;
 
 import java.io.File;
@@ -76,6 +77,10 @@ public interface Configuration
 
     Configuration setClassLoader( ClassLoader loader );
 
+    PlexusContainer getParentContainer();
+
+    Configuration setParentContainer( PlexusContainer parentContainer );
+
     // ----------------------------------------------------------------------------
     // Profiles
     // ----------------------------------------------------------------------------

maven-embedder/src/main/java/org/apache/maven/embedder/DefaultConfiguration.java

@@ -18,6 +18,7 @@
  * under the License.
  */
 
+import org.codehaus.plexus.PlexusContainer;
 import org.codehaus.plexus.classworlds.ClassWorld;
 
 import java.io.File;
@@ -53,6 +54,8 @@ public class DefaultConfiguration
 
     private ClassWorld classWorld;
 
+    private PlexusContainer parentContainer;
+
     private File localRepository;
 
     /** Creates a new instance of DefaultConfiguration */
@@ -189,6 +192,17 @@ public Configuration setClassLoader( ClassLoader loader )
         return this;
     }
 
+    public PlexusContainer getParentContainer()
+    {
+        return parentContainer;
+    }
+
+    public Configuration setParentContainer( PlexusContainer parentContainer )
+    {
+        this.parentContainer = parentContainer;
+        return this;
+    }
+
     // ----------------------------------------------------------------------------
     // Local Repository
     // ----------------------------------------------------------------------------

maven-embedder/src/main/java/org/apache/maven/embedder/MavenEmbedder.java

@@ -557,7 +557,7 @@ private void start( Configuration configuration )
         try
         {
             ContainerConfiguration cc = new DefaultContainerConfiguration()
-                .setClassWorld( classWorld );
+                .setClassWorld( classWorld ).setParentContainer( configuration.getParentContainer() );
 
             container = new DefaultPlexusContainer( cc );
         }