docs: private boolean setChild1(N newChild) {
  		if (this.child1 == newChild) {
  			return false;
  		}
  
  		if (this.child1 != null) {
  			this.child1.setParentNodeReference(null, true);
  			--this.notNullChildCount;
  			firePropertyChildRemoved(0, this.child1);
  		}
  
  		if (newChild != null) {
  			final N oldParent = newChild.getParentNode();
  			if (oldParent != this) {
  				newChild.removeFromParent();
  			}
  		}
  
  		this.child1 = newChild;
  
  		if (newChild != null) {
  			newChild.setParentNodeReference(toN(), true);
  			++this.notNullChildCount;
  			firePropertyChildAdded(0, newChild);
  		}
  
  		return true;
  	}