code: @Override
      public ResultSet getExportedKeys( String catalog,
                                        String schema,
                                        String table ) throws SQLException {
          return getImportedKeys(catalog, schema, table); // empty, but same resultsetmetadata
      }
docs: {@inheritDoc}
  <p>
  This driver maps REFERENCE properties as keys, and therefore it represents as imported keys those REFERENCE properties on
  the type identified by the table name.
  </p>
  
  @see java.sql.DatabaseMetaData#getExportedKeys(java.lang.String, java.lang.String, java.lang.String)