Something a bit wrong with `@DBusBoundProperty` about dbus-java HOT 9 OPEN

I've looked at this case and I agree that something is missing here.

I first investigated what you mentioned about PropRefRemoteHandler.
When the method handleDBusBoundProperty is used it is assumed that Properties is supported by the given remote object.

That is wrong. The remote object the method receives is an arbitrary object which is not necessarily related to Properties.
In most cases the object behind the remote path is supporting Properties but not necessarily the object passed to this method.

So your fix to create another remote object using Properties will work because the calls are delegated to the object behind the path, not to the given object itself.

For me this seems to be a valid fix. Some tests would be great, but how to test a thing which did work before?

The second thing you mentioned is Marshalling class.
I have to admit I don't see why there is a need to change anything. Also I'm not sure what your change should do. When debugging this the parameter is not Variant it is String so the code will never be executed.

The right fix for this is again in PropRefRemoteHandler.
When handleDBusBoundProperty has executed the remote method call, it must take care of the result.

What is happening here?
The remote call will (hopefully) resolve the requested property and as the javadoc on that method already says, all properties on DBus are always Variant.
Variant may not be the type of object we want to return here. This depends on how the @DBusBoundProperty was used (e.g. the return of the method is Variant).

So we may have to unwrap the Variant here to get the correct object type:

Object result = null;

if (access == Access.READ) {
    result = RemoteInvocationHandler.executeRemoteMethod(propertiesRemoteObj, PROP_GET_METHOD,
            new Type[] {_method.getGenericReturnType()}, _conn, RemoteInvocationHandler.CALL_TYPE_SYNC, null, DBusNamingUtil.getInterfaceName(_method.getDeclaringClass()), name);
} else {
    result = RemoteInvocationHandler.executeRemoteMethod(propertiesRemoteObj, PROP_SET_METHOD, variantType,
            new Type[] {_method.getGenericReturnType()}, _conn, RemoteInvocationHandler.CALL_TYPE_SYNC, null, DBusNamingUtil.getInterfaceName(_method.getDeclaringClass()), name, _args[0]);
}

// requested return type is not Variant but the result is -> unwrap Variant
if (_method.getReturnType() != Variant.class && typeClass != Variant.class && result instanceof Variant<?> v) {
    return v.getValue();
}

return result;

I've already updated master branch to include this patch and your patch as well.

from dbus-java.

I did some more work on this stuff.
I found that there are some combinations of implementing Properties and using @DBusBoundProperty annotation which will not work or will not produce the expected results.
Especially some instanceof checks with @DBusProperties annotations were definitely wrong as no object exported on/to the bus can/will ever be a subclass of an annotation.

All changes are already in master branch so you can try it when the new snapshot is deployed to snapshot repository.

from dbus-java.