code: void closeConnection(final PoolEntry poolEntry, final String closureReason)
     {
        if (connectionBag.remove(poolEntry)) {
           final Connection connection = poolEntry.close();
           closeConnectionExecutor.execute(() -> {
              quietlyCloseConnection(connection, closureReason);
              if (poolState == POOL_NORMAL) {
                 fillPool();
              }
           });
        }
     }
docs: Permanently close the real (underlying) connection (eat any exception).
  
  @param poolEntry poolEntry having the connection to close
  @param closureReason reason to close