Unable to remove request participant via REST API when reporter is on the list

Summary

Users are unable to remove any request participant via REST API when the reporter is on that list.

Environment

• CLOUD 3.3.0-OD-1000.564.0
• REST API 1000.445.0
• REST API latest - https://docs.atlassian.com/jira-servicedesk/REST/cloud/#servicedeskapi

Steps to Reproduce

1. Create a ticket via REST API where the reporter is listed on the request participant's list. E.g. POST:

   https://INSTANCE.atlassian.net/rest/servicedeskapi/request
   {
       "serviceDeskId": "2",
       "requestTypeId": "16",
       "requestFieldValues": {
           "summary": "Request JSD help via REST 2",
           "description": "I need a new mouse for my Mac"
       },
       "requestParticipants": [
           "user1",
         	"MyReporter"
       ]
   }

2. Now try to remove any other participant from the list. E.g. DELETE:

   https://INSTANCE.atlassian.net/rest/servicedeskapi/latest/request/JSD-44/participant
   {
       "usernames": [
           "user1"
       ]
   }

Expected Results

• The user should be removed from the request participant's list.
  < OR >
• The error message should be clear on what the problem actually is.

Actual Results

The following error message shows up:

{
    "errorMessage": "Failed to update request participants field, errors: ",
    "i18nErrorMessage": {
        "i18nKey": "sd.request.participants.error.field.update.failed",
        "parameters": [
            ""
        ]
    }
}

Notes:

• Via UI it's possible to remove that user from the request participant's list.
• The problem only happens when the reporter is also into the request participant's list.

Workaround

Do not add the reporter into the request participant's list.