UNKNOWN(String requestLine) This function will be called by the
serverCore .listen() function
if no corresponding funktion of the serverHandler class can be
found for the received command.
Tthis function will be called by the
serverCore .listen() function
if the whole request line is empty and therefore no function of this
serverHandlerClass can be called because of the missing command name
This function will be called by the
serverCore .listen() function
if no corresponding funktion of the serverHandler class can be
found for the received command.