Hoverfly replaces "Host" header in SPY mode #1013

Description of the bug

I am using hoverfly-java (0.14.0) with my Spring project in integration testing.
My actual service (under test/spy) calls are routed through envoy which relies on the Host: X header - where X specifies the service name.
For example, this is the original request:

{
    "method" : "GET",
    "url" : "http://localhost:9211/sample-path/1",
    "queryStringParameters" : {},
    "headers" : {
      "Host" : [ "my-service.service" ],
      "Accept" : [ "application/json" ]
    }
  }

While using Hoverfly in SPY mode, it is proxying requests but replacing the Host header to finally have this request:

{
    "method" : "GET",
    "url" : "http://localhost:{hoverlfy-port}/sample-path/1",
    "queryStringParameters" : {},
    "headers" : {
      "Host" : [ "localhost:9211" ],
      "Accept" : [ "application/json" ]
    }
  }

This makes the underlying service unable to route requests.

Is it possible to specify custom header for Hoverfly to use internally for forwarding requests? Or can I explicitly re-set the header using a hack?

Steps to reproduce the issue

I can upload a sample project in the discussion below - however, the issue is easy to reproduce with SPY mode.

Observed result

404 Not Found due to wrong Host header

Expected result

200 OK