bug fix for null pointer exception if service.compose is called directly

org.fortiss.tooling.kernel/trunk/src/org/fortiss/tooling/kernel/internal/ElementCompositorService.java

@@ -20,6 +20,7 @@ package org.fortiss.tooling.kernel.internal;
 import java.util.List;
 
 import org.eclipse.emf.ecore.EObject;
+import org.fortiss.tooling.kernel.ToolingKernelActivator;
 import org.fortiss.tooling.kernel.extension.IElementCompositor;
 import org.fortiss.tooling.kernel.extension.data.IElementCompositionContext;
 import org.fortiss.tooling.kernel.extension.data.Prototype;
@@ -27,6 +28,7 @@ import org.fortiss.tooling.kernel.model.ILibraryElementReference;
 import org.fortiss.tooling.kernel.service.IElementCompositorService;
 import org.fortiss.tooling.kernel.service.IPersistencyService;
 import org.fortiss.tooling.kernel.service.base.EObjectAwareServiceBase;
+import org.fortiss.tooling.kernel.utils.LoggingUtils;
 
 /**
  * This class implements the {@link IElementCompositorService} interface.
@@ -34,7 +36,7 @@ import org.fortiss.tooling.kernel.service.base.EObjectAwareServiceBase;
  * @author hoelzl
  * @author $Author$
  * @version $Rev$
- * @ConQAT.Rating GREEN Hash: 60984ED04677CEB022C01A46081438E4
+ * @ConQAT.Rating YELLOW Hash: 92E1A4E58E91DC08258B83B53E3034D2
  */
 public final class ElementCompositorService extends
 		EObjectAwareServiceBase<IElementCompositor<EObject>> implements IElementCompositorService {
@@ -64,6 +66,12 @@ public final class ElementCompositorService extends
 	public boolean compose(EObject container, EObject element, IElementCompositionContext context) {
 		IElementCompositor<EObject> compositor =
 				findWorkingCompositor(container, element, context, false);
+		if(compositor == null) {
+			LoggingUtils.error(ToolingKernelActivator.getDefault(), String.format(
+					"Can not find compositor for container %s and element %s",
+					container.getClass(), element.getClass()));
+			return false;
+		}
 		IPersistencyService.INSTANCE.getTopLevelElementFor(container).prepareIDs(element);
 		return compositor.compose(container, element, context);
 	}