adds guard in cases fixes are null

refs 2553

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

@@ -37,7 +37,7 @@ import org.fortiss.tooling.kernel.utils.LoggingUtils;
  * @author aravantinos
  * @author $Author$
  * @version $Rev$
- * @ConQAT.Rating YELLOW Hash: 1E06A3A4ED3DFC3F6DF9D4345FB29D7D
+ * @ConQAT.Rating YELLOW Hash: 3B08090E073A0A96815E002991A128A7
  */
 public final class ConstraintVerificationService extends
 		EObjectAwareServiceBase<IConstraintVerifier<IConstraint>> implements
@@ -59,13 +59,14 @@ public final class ConstraintVerificationService extends
 	/** {@inheritDoc} */
 	@Override
 	public List<IFix> fixes(IConstraintVerificationStatus status) {
+		List<IFix> fixes = null;
 		if(status != null) {
 			IConstraintVerifier<IConstraint> verifier = getFirstVerifier(status.getConstraint());
 			if(verifier != null) {
-				return verifier.fixes(status);
+				fixes = verifier.fixes(status);
 			}
 		}
-		return new ArrayList<IFix>();
+		return fixes != null ? fixes : new ArrayList<IFix>();
 	}
 
 	/**