public Builder listeningPort(final int listeningPort) {
      return listeningPort(Optional.of(listeningPort));
    }
An listening port value. A value of 0 means the node is not listening.

@param listeningPort If non-zero, represents the port on which to listen for connections. A
    value of 0 means the node is not listening for connections.
@return The modified builder
ethereum/p2p/src/main/java/org/hyperledger/besu/ethereum/p2p/peers/EnodeURLImpl.java