diff string is empty in API output while comparing with commits in Gitlab 13.2.8

Hi Folks,

I am trying to get the diff output for my MR commits using API (GET /projects/:id/repository/compares).

Ex: https://gitlabe.myinstacne.com/api/v4/projects/116/repository/compare?from=084c816&to=3078a3e

But output string returned with empty string, anyway GUI is showing it's diff correctly.

  "old_path":"vendor/github.com/davecgh/go-spew/spew/common.go",
  "new_path":"vendor/github.com/davecgh/go-spew/spew/common.go",
  "a_mode":"0",
  "b_mode":"100644",
  "new_file":true,
  "renamed_file":false,
  "deleted_file":false,
  "diff":""
}

Is there any workaround for this issue/bug ?