Postman mock server not displaying headers with underscore in the name

I’ve been using a mock server to test some edge/error cases for an http client.
When I enter a header that contains an underscore in the header name, the mock server does not display it. Is this expected behaviour?

Steps to reproduce

  1. create a mock server
  2. create a request towards the mock server URL setting a header as “X-SW_HDR1:abcd1234” using postman client
  3. click send
  4. check postman console and the header can be seen
  5. check the postman mock server and the header is not displayed.