ObjectSinkNode currentSink = this.hashableSinks.getFirst();
while ( currentSink != null ) {
final AlphaNode alphaNode = (AlphaNode) currentSink;
final AlphaNodeFieldConstraint fieldConstraint = alphaNode.getConstraint();
final IndexableConstraint indexableConstraint = (IndexableConstraint) fieldConstraint;
// position to the next sink now because alphaNode may be removed if the index is equal. If we were to do this
// afterwards, currentSink.nextNode would be null
currentSink = currentSink.getNextObjectSinkNode();