@Override
  public boolean isPossibleDuplicate() {
    return isPossibleDuplicate;
  }
Returns subset of keys provided by the invoking thread (aka routing objects) which may exist in
the local data set.

@see Execution#withFilter(Set)

@return the objects should be local to this context
geode-core/src/main/java/org/apache/geode/internal/cache/execute/RegionFunctionContextImpl.java