The content-type used in the Xray internal endpoint is not coherent with the format used in the Body

Description
For some Xray internal endpoints used in the Execution details page, the Body passed is not according to the content-type passed in the Request header, that usually is: "application/json".
Some customers use a tool that validates all the requests done in the network (Jira <-> Xray), to know if the content-type passed in the header is according to the format of the Body passed, and it fails.

How to reproduce

1. Go to the Test Execution details page
2. Try to add a new comment there and check the "Content-type" passed in the Request header and the format of the Body

Actual result/Attachments

Expected result
The expected result is that the Body passed in this request be a valid JSON

Version

• Xray 4.2.11

Environment

• Jira 8.6.0