Cannot retrieve interfaces from /_/proxy/tenants/<tenant>/interfaces (400 status code)

Steps to reproduce:

1. Authorize by running the following request in Postman:
   POST <<Kong base URL>>/authn/login-with-expiry
   Body:
   {
   "username": "<<admin username>>",
   "password": "<<admin password>>"
   }
   "x-okapi-tenant" header: "diku4"

2. Run the following request:

GET <<Kong base URL>>/_/proxy/tenants/<<same tenant name/id>>/interfaces

Expected result:
Response with "200" status returned. The interfaces can be retrieved.

Actual result:
Response with “400” status is returned:

{
"errors": [
{
"message": "Expected URL scheme 'http' or 'https' but no scheme was found for /mgr-t...",
"type": "IllegalArgumentException",
"code": "validation_error"
}
],
"total_records": 1
}