Page Model API gives 500 in preview when X-Forwarded-Host is present

Context:
When we run an SPA, we usually use a standalone cms host configuration with multiple channels. In this case, the SPA is running somewhere on a different host and requests the Page Model API served from another host.

Way to Reproduce:
1. Run the HAP.
2. Go to the Experience Manager.
3. Click on "React SSR SPA".
4. Copy the JSESSIONID cookie for "/site" path.
5. Open a terminal.
6. Run the following command:

curl -X GET \
  http://127.0.0.1:9080/site/_cmsinternal/spa-react-ssr/resourceapi \
  -H 'cookie: JSESSIONID=44053911553CB27FE45316592EBC35A8' \
  -H 'x-forwarded-host: spa.example.com'

Actual::

• 500 error is being returned.
• The output from the CMS console:

  [INFO] [talledLocalContainer] 18.12.2019 13:00:22 WARN  http-nio-9080-exec-7 [HstDelegateeFilterBean.doFilter:511] Co│
  ntainerException for 'Request{ method='GET', scheme='http', host='127.0.0.1', requestURI='/site/_cmsinternal/spa-reac│
  t-ssr/resourceapi', queryString='null'}': org.hippoecm.hst.core.container.ContainerException: java.lang.IllegalArgume│
  ntException: Could not match cms host 'spa.example.com' in platform hst model (through reference chain: org.hippoecm.│
  hst.pagemodelapi.v09.core.model.ComponentWindowModel["components"]->java.util.LinkedHashSet[0]->org.hippoecm.hst.page│
  modelapi.v09.core.model.ComponentWindowModel["components"]->java.util.LinkedHashSet[0]->org.hippoecm.hst.pagemodelapi│
  .v09.core.model.ComponentWindowModel["components"]->java.util.LinkedHashSet[0]->org.hippoecm.hst.pagemodelapi.v09.cor│
  e.model.ComponentWindowModel["models"]->java.util.LinkedHashMap["document"])  
  

Expected:

• Page Model API should ignore `x-forwarded-host` header or return 404.