Review Java Android App project.

I'm looking to hire an Android development Consultant, I'm developing an Android application, however, I have no experience with the platform whatsoever and I would like to have someone do a code-review and produce a document with feedback and recommendations on how to improve the current codebase so that it follows best practices and up-to-date standards.

The application's code base is not large, it does not have any screen-heavy logic, however, it integrates with accessibility services, MQTT Messaging and other not-so-standard functionality.