class GrantRevokeIndex {

    GrantRevokeIndex overrideBy(final GrantRevokeIndex update) {
        checkNotNull(update, "update");
        grantMap.addAllEntriesFrom(update.grantMap).removeAllEntriesFrom(update.revokeMap);
        revokeMap.removeAllEntriesFrom(update.grantMap).addAllEntriesFrom(update.revokeMap);
        return this;
    }

      GrantRevokeIndex();
      GrantRevokeIndex(final PermissionSubjectsMap grantMap, final PermissionSubjectsMap revokeMap);

}