/**
  * Use this with extreme care, to add filters to this variable..
  *
  * @param pointerKey The pointerKey to set.
  */
 void setPointerKey(PointerKey pointerKey) {
   // check that we haven't modified the hash code!!! this is crucial
   assert this.pointerKey.hashCode() == pointerKey.hashCode();
   this.pointerKey = pointerKey;
 }