[New] Added GroupedParameterizedElement.isRelationSet()

li.strolch.model/src/main/java/li/strolch/model/GroupedParameterizedElement.java

@@ -960,6 +960,17 @@ public abstract class GroupedParameterizedElement extends AbstractStrolchElement
 		return bag.hasParameter(paramKey);
 	}
 
+	@Override
+	public boolean isRelationSet(String paramKey) {
+		if (this.parameterBagMap == null)
+			return false;
+		ParameterBag bag = this.parameterBagMap.get(BAG_RELATIONS);
+		if (bag == null)
+			return false;
+		StringParameter relationP = bag.getStringP(paramKey);
+		return relationP != null && relationP.isSet();
+	}
+
 	@Override
 	public boolean hasParameter(String bagKey, String paramKey) {
 		if (this.parameterBagMap == null) {

li.strolch.model/src/main/java/li/strolch/model/ParameterBagContainer.java

@@ -1624,6 +1624,19 @@ public interface ParameterBagContainer extends StrolchElement {
 	 */
 	boolean hasRelation(String paramKey);
 
+	/**
+	 * Returns true if the {@link Parameter} with the given paramKey exists on the {@link ParameterBag} with the id
+	 * {@link StrolchModelConstants#BAG_RELATIONS} and the value of the parameter is also set, i.e. not empty
+	 *
+	 * @param paramKey
+	 * 		the key of the {@link Parameter} to be found
+	 *
+	 * @return true if the {@link Parameter} with the given paramKey exists on the {@link ParameterBag} with the given
+	 * bagKey and the value of the parameter is also set, i.e. not empty. False is returned if the {@link ParameterBag} does not exist, the {@link Parameter} does not exist on
+	 * the {@link ParameterBag}, or the value of the parameter is empty
+	 */
+	boolean isRelationSet(String paramKey);
+
 	/**
 	 * Returns true if the {@link Parameter} with the given paramKey exists on the {@link ParameterBag} with the given
 	 * bagKey