Kernel: Improved comments and added util

Fixed review comments.

Issue-ref: 4244
Issue-URL: af3#4244

Signed-off-by: Andreas Bayha <bayha@fortiss.org>

org.fortiss.tooling.ext.variability/src/org/fortiss/tooling/ext/variability/util/.ratings

-VariabilityUtils.java 8ac97aafcbc2409ee39a5d9ee85f234a49bb2079 RED
+VariabilityUtils.java ccbcc8a13557a107608130e25880f9523b84cfba YELLOW

org.fortiss.tooling.ext.variability/src/org/fortiss/tooling/ext/variability/util/VariabilityUtils.java

@@ -16,6 +16,7 @@
 package org.fortiss.tooling.ext.variability.util;
 
 import static org.fortiss.tooling.ext.variability.model.VariabilityModelElementFactory.createOptionalVariationPointSpecification;
+import static org.fortiss.tooling.kernel.utils.EcoreUtils.getFirstChildWithType;
 import static org.fortiss.tooling.kernel.utils.EcoreUtils.pickFirstInstanceOf;
 
 import org.eclipse.emf.ecore.EObject;
@@ -71,17 +72,14 @@ public class VariabilityUtils {
 			return true;
 		}
 
-		// TODO (TM): Use the methods provided by the `EcoreUtils`. `isAncestor()` can replace the
-		// check whether the `eContainer` is `null` and `getFirstChildWithType()` can be used to see
-		// whether any `AbstractFeatureModel` is present.
-
-		// Check whether the root container contains any AbstractFeatureModel
+		// Find the root container (usually a FileProject)
 		EObject topLevelElem = element;
 		while(topLevelElem.eContainer() != null) {
 			topLevelElem = topLevelElem.eContainer();
 		}
 
-		return topLevelElem.eContents().stream().anyMatch(c -> c instanceof AbstractFeatureModel);
+		// Check whether this root container contains any AbstractFeatureModel.
+		return getFirstChildWithType(topLevelElem, AbstractFeatureModel.class) != null;
 	}
 
 	/**