*<Null safety>*
Function? getCallback (int txid)
Returns the callback associated with the given response message.
Used by subclasses of Proxy<T> to retrieve registered callbacks when handling response messages.
Implementation
Function? getCallback(int txid) {
final Function? result = _callbackMap.remove(txid);
if (result == null) {
proxyError('Message had unknown request id: $txid');
return null;
}
return result;
}