@Override
  public WriteResult call() throws Exception {
    if (keys.isEmpty()) {
      return WriteResult.empty();
    }

    // special case for single key delete
    // Not using removeAll() because one can know if element was deleted based on return of remove()
    // this return is used for WriteResult statistics
    if (keys.size() == 1) {
      boolean removed = session.region.remove(keys.iterator().next()) != null;
      return WriteResult.empty().withDeletedCount(removed ? 1 :0);
    }
    session.region.removeAll(keys);
    return WriteResult.unknown();
  }
Responsible for delete by key. Using bulk API

@see Region#removeAll(Collection)
criteria/geode/src/org/immutables/criteria/geode/SyncDeleteByKey.java