ps.set(index, prop);
otherProperties.set(index, prop);
  private final synchronized void addOrReplaceLocalPG(PropertyGroup prop) {    // Look through the list for a PG of a matching class.  The hard part    // of this is that either the prop or any of the elements of the list    // may be natural (FooPGImpl), locked, Null, etc.  So: our solution is    // to compare the "PrimaryClass" of each.    int index = findLocalPGIndex(prop.getPrimaryClass());    ArrayList ps = force();    if (index >= 0) {      ps.set(index, prop);    } else {      ps.add(prop);    }  }