The MessageHandler should not return `null` but throw a `DBusException`

[swiesend]

My new MessageHandler avoids returning null on my 2.0.0 branch as this only leads to problems, if the case is not handled properly.

kdewallet/src/main/java/org/freedesktop/dbus/handlers/MessageHandler.java

Lines 30 to 55 in acd9595

	public Object[] send(String service, String path, String iface, String method, String signature, Object... args) {
	try {
	org.freedesktop.dbus.messages.Message message = new MethodCall(
	service,
	path,
	iface,
	method, (byte) 0, signature, args);
	connection.sendMessage(message);
	org.freedesktop.dbus.messages.Message response = ((MethodCall) message).getReply(2000L);
	log.trace(response.toString());
	if (response instanceof org.freedesktop.dbus.errors.Error) {
	throw new DBusException(response.getName() + ": " + response.getParameters()[0]);
	}
	Object[] parameters = response.getParameters();
	log.debug(Arrays.deepToString(parameters));
	return parameters;
	} catch (DBusException e) {
	log.error(e.toString(), e.getCause());
	}
	return null;
	}

see: https://github.com/swiesend/secret-service/blob/c7399ea1f2d6031158a64a0459a066a35c7f9cbf/src/main/java/org/freedesktop/secret/handlers/MessageHandler.java#L34-L75

see also: swiesend/secret-service#6

[purejava]

Thanks for pointing me to the upcoming new release with the improved MessageHandler. It‘s good to have a DBusException instead of returning null in case of MessageHandler having problems sending a message via D-Bus. This will add good robustness to the library for cases where the whole D-Bus back-end fails.
I‘ll adopt your changes when they are released.

Anyway, kdewallet does not have the same challenges secret-service has concerning the handling of org.freedesktop.Secret.Errors within MessageHandler, as they just do not exist in the wallet / KDE context.

Cheers!