bugfix: constraint service interface was too specific, implementation produced NPE

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

@@ -77,8 +77,12 @@ public class ConstraintService extends
 	 */
 	private void performConstraintCheck(EObject modelElement,
 			List<IConstraintViolation<EObject>> violationList) {
-		for (IConstraintChecker<EObject> checker : getRegisteredHandlers(modelElement
-				.getClass())) {
+		List<IConstraintChecker<EObject>> handlers = getRegisteredHandlers(modelElement
+				.getClass());
+		if (handlers == null) {
+			return;
+		}
+		for (IConstraintChecker<EObject> checker : handlers) {
 			if (checker.isApplicable(modelElement)) {
 				IConstraintViolation<EObject> violation = checker
 						.apply(modelElement);

org.fortiss.tooling.kernel/trunk/src/org/fortiss/tooling/kernel/services/IConstraintService.java

@@ -43,8 +43,8 @@ public interface IConstraintService {
 	 * its content and returns the check results. Note, that this method can be
 	 * time-consuming for large model element trees.
 	 */
-	<T extends EObject> List<IConstraintViolation<T>> performAllConstraintChecksRecursively(
-			T modelElement);
+	List<IConstraintViolation<EObject>> performAllConstraintChecksRecursively(
+			EObject modelElement);
 
 	/**
 	 * Performs all constraint checks only on the given model element and