Java 1293

### Features todo:

- [x] Remove acknowledged flag.
- [x] Support Multiple writes at same time
- [x] Sync support 
        
### Tests 
- [ ] Mock stream.
- [ ] Multiple threads hammering the connection....
- [ ] Test multiple writes - with mocked stream to confirm it waits
- [ ] Test mix of async and sync reads / writes
- [ ] Test out of order responses