code: public synchronized void close() {
          for (PreparedStatement ps : threadedPsMap.get().values()) {
              if (null != ps) {
                  try {
                      ps.close();
                  } catch (SQLException e) {
                      // swallowed
                  }
              }
          }
          try {
              if (null != connection) {
                  this.connection.close();
              }
          } catch (SQLException e) {
              // swallowed
          }
      }
docs: Closes all cached {@link PreparedStatement} objects and then
  closes the database {@link Connection}.
  
  <p>
  This must be called before the instance goes out of scope.
  </p>