one issues Tadeas identified during testing sender endpoint via Java Sender lib is connected to this quiet change in the REST response from REST Sender endpoint (we added text/plain response specification):

As we were always responding with "Job submitted", admin-ui client started to complain about the response not being JSON. So obvious fix was change that to text/plain, right?

Not really.. some clients like Java Sender lib already expects application/json and JAX-RS then refuses these requests:

The question is, what should be the correct response?

There are many options, I would be perfectly fine with 204 No Content reply,

but JSON might be more appropriate for future extensions, we may want to return e.g. PushMessageInformation#id or something else as part of the response.

So, wouldn't be application/json more appropriate than text/plain? We may send empty body now {}.

Is this something we want to address for Alpha? Or should we release fixed Java Sender lib?

Cheers,

~ Lukas