code: private final void addHandle(WSJdbcConnection handle) throws ResourceException {
          (numHandlesInUse < handlesInUse.length - 1 ? handlesInUse : resizeHandleList())[numHandlesInUse++] = handle;
          if (!inRequest && dsConfig.get().enableBeginEndRequest)
              try {
                  inRequest = true;
                  mcf.jdbcRuntime.beginRequest(sqlConn);
              } catch (SQLException x) {
                  FFDCFilter.processException(x, getClass().getName(), "548", this);
                  throw new DataStoreAdapterException("DSA_ERROR", x, getClass());
              }
      }
docs: Add a handle to this ManagedConnection's list of handles.
  Signal the JDBC 4.3+ driver that a request is starting.
  
  @param handle the handle to add.
  @throws ResourceException if a JDBC 4.3+ driver rejects the beginRequest operation