Java Backend Testing Automation Framework

As a client, I am in need of a skilled Java developer to design and implement a robust automation framework for backend testing using RestAssured. This framework's primary focus will be on functional testing and should integrate with TestNG.

Key Requirements:
- Solid understanding and knowledge of Java.
- Experience with RestAssured for backend testing.
- Familiarity with TestNG testing framework.
- A focus on functional testing to validate the backend system functionality.

The ideal freelancer will be one well-versed in backend testing, able to effectively utilize Java and TestNG, and can deliver a functional, clean, and well-documented test automation codebase.