title: Angular access to headers from activatedRoute (or similar?)
body: <p>I tired looking around but couldn't find any solution.</p>
  
  <p>From Angular (using v7), how can I retrieve the request HEADERS from an activatedRoute?</p>
  
  <p>My use case is that an authentication provider calls my Angular page and provides the uuid of the user activated via the <code>referrer request header</code>, which I need to retrieve.</p>
  
  <p>I've used the <code>activatedRoute</code> for <em>query parameters</em>, but it doesn't seem to provide a way to query <strong>headers</strong>.
  I was thinking also to use the <code>Routes</code>, but it doesn't seem possible to access the headers over there too.</p>
  
  <p>Thanks!</p>