422 unprocessable entry on java based project API

I am in need of a Java developer to help me resolve a "422 Unprocessable Entry" error message on a custom-built API for my project. I do not have documentation on the API's expected inputs and outputs, so the ideal candidate should have experience in analyzing and debugging code to identify and fix issues. The following skills and experience are required for this project:

- Java programming
- Experience with custom-built APIs
- Debugging and troubleshooting skills

If you have experience with resolving similar issues or have worked on similar projects, please apply for this job.