Expose the PUBACK ReasonString #300
Description
🚀 Feature Request
When using Schema validation on HiveMQ cloud, payloads which fail validation returns a ReasonCode and ReasonString, but only ReasonCode is available from this library.
From a developers/user point of view its really helpful to understand what specific element failed (i.e. UserName was greater than 20 characters). This feels like a big oversight in this library.
Additionally, having a quick look at your Java implementation, I believe you do expose ReasonString.
🔈 Motivation
The HiveMQ broker is being used, in our case, as an API for Integrators of our system, so having this information for them to diagnose their mistakes is really useful.
🛰 Alternatives
Use another library (MQTTnet support this), but we would like to recommend a few options.