@Override
  public boolean containsTombstone(Object key) {
    checkReadiness();
    checkForNoAccess();
    if (!getConcurrencyChecksEnabled()) {
      return false;
    }
    try {
      Entry entry = getDataView().getEntry(getKeyInfo(key), this, true);
      return entry != null && entry.getValue() == Token.TOMBSTONE;
    } catch (EntryDestroyedException ignore) {
      return true;
    }
  }
return a set of the keys in this region

@param allowTombstones whether destroyed entries should be included
@return the keys
geode-core/src/main/java/org/apache/geode/internal/cache/LocalRegion.java