Java Client should not return null for 404 responses

[steven-barnes]

For code like:

subscriptionApi.getSubscriptionByKey("xyzzy", requestOptions)

The client returns null on 404 errors. This is unexpected. The client should throw a KillBillClientException containing the response code.

[pierre]

Yes, we've talked about enhancing this in the past. This behaviour has been in place for 12+ years though, so it'd be a large breaking change.