code: @Override
      public boolean isClosed() throws SQLException {
          if (!isClosed) {
              try {
                  if (internalConn.isClosed()) {
                      destroy();
                  }
              } catch (SQLException e) {
                  // ignore
                  destroy();
  
                  if (logger.isWarnEnabled()) {
                      logger.warn(AbacusException.getErrorMsg(e));
                  }
              }
          }
  
          return isClosed;
      }
docs: Method isClosed.
  
  @return boolean
  @throws SQLException
  @see java.sql.Connection#isClosed()