private Optional<RequestManager> getRequestManager(final String protocolName, final int code) {
    if (requestManagers.containsKey(protocolName)) {
      final Map<Integer, RequestManager> managers = requestManagers.get(protocolName);
      final Integer requestCode = roundMessages.getOrDefault(code, -1);
      if (managers.containsKey(requestCode)) {
        return Optional.of(managers.get(requestCode));
      }
    }
    return Optional.empty();
  }
Attempt to get a request manager for a received response-type message e.g. BLOCK_HEADERS. If
the message is a request-type message e.g. GET_BLOCK_HEADERS no request manager will exist so
Optional.empty() will be returned.

@param protocolName the type of protocol the message is for
@param code the message code
@return a request manager for the received response message, or Optional.empty() if this is a
    request message
ethereum/eth/src/main/java/org/hyperledger/besu/ethereum/eth/manager/EthPeer.java