How to send GET request with body?

I am trying to send a GET request with a body, but I receive the error: "Request with GET/HEAD method cannot have body."

I know that sending a GET request with a body is unusual, but I need to do it because of a legacy requirement.
What should I do?

The issue identifies no files, tests, or entry points. Start by locating the GET/HEAD request validation in the datasource-rest request path and determine whether legacy GET bodies are intended to be supported or documented as unsupported. Done means the expected behavior is defined and covered by an appropriate test or documentation change.

Written by the indexing model from the issue text.