Thanks! Will review ASAP.

Not sure if the changes to the lowlevel mappings are required here?! You're also changing the version of Natives.initializer in use - potentially to the correct one.

The old invocation of Native.initializer(ptr, false, false) is where memory leak introduced. Following code creates a not owned promise in java.

Promise promise = new Promise(new Promise.PROMISE_CHANGE() {
    @Override
    public void onChange(Promise promise) {
    }
});

GstPromise * gst_promise_new_with_change_func (GstPromiseChangeFunc func, gpointer user_data, GDestroyNotify notify) has two additional parameters, while its java corresponding GstPromiseAPI.gst_promise_new_with_change_func doesn't. When we construct promise using java version, we pass only one argument, C version got random user_data, notify from registers or stacks. Thus in gst_promise_free we may got SIGBUS or SIGSEGV due to random notify.

Current version got no coredump due to memory leak, aka. no gst_promise_free at all.