container/services/src/main/java/org/mobicents/slee/runtime/sbbentity/ChildRelationImpl.java
private void validateChildName(String childName) throws IllegalArgumentException, NullPointerException {
    	if (childName == null) {
    		throw new NullPointerException("null child name"); 
    	}
    	if (childName.isEmpty()) {
    		throw new IllegalArgumentException("empty child name");
    	}
    }
private void validateChildName(String childName) throws IllegalArgumentException, NullPointerException {
    	if (childName == null) {
    		throw new NullPointerException("null child name"); 
    	}
    	if (childName.isEmpty()) {
    		throw new IllegalArgumentException("empty child name");
    	}
    }
extension methods