Protect against null sources
diff --git a/org.eclipse.sisu.plexus/src/org/eclipse/sisu/plexus/RealmFilteredBeans.java b/org.eclipse.sisu.plexus/src/org/eclipse/sisu/plexus/RealmFilteredBeans.java
index 70d78d0..69994f6 100644
--- a/org.eclipse.sisu.plexus/src/org/eclipse/sisu/plexus/RealmFilteredBeans.java
+++ b/org.eclipse.sisu.plexus/src/org/eclipse/sisu/plexus/RealmFilteredBeans.java
@@ -96,7 +96,7 @@
             while ( itr.hasNext() )
             {
                 nextBean = itr.next();
-                final String source = nextBean.getSource().toString();
+                final String source = String.valueOf( nextBean.getSource() );
                 if ( !source.startsWith( "ClassRealm" ) || realmNames.contains( source ) )
                 {
                     return true;