@Override public GraphQuery has(final String key,final Predicate predicate,final Object value){
  if (!knownPredicates.contains(predicate.getClass())) {
    throw new IllegalArgumentException();
  }
  criteria.add(new Has(key,value,BigdataPredicate.toBigdataPredicate(predicate)));
  return this;
}

@ Override public GraphQuery has ( final String key , final Predicate predicate , final Object value ) { if ( ! knownPredicates . contains ( predicate . getClass ( ) ) ) { throw new IllegalArgumentException ( ) ; } criteria . add ( new Has ( key , value , BigdataPredicate . toBigdataPredicate ( predicate ) ) ) ; return this ; }
filter out the element if it does not have a property with a comparable value .
