Set x-frames-options header values depending on URI

Hello,

I am trying to write an irule that sets the x-frame-options header value to SAMEORIGIN or a site, unless the URI contains a specific string. In that case I would want the x-frames-option value to be set to ALLOW. The code I have so far is show below, but the header value is always set to SAME origin when I examine headers on the client side, but I'm not sure what I'm missing:

when HTTP_REQUEST {

  if { [string tolower [HTTP::uri]] contains "/docsAPI" } {

    set insertXFrame 1

  }

  else {

    set insertXFrame 0

  }

}

when HTTP_RESPONSE {

  if {!([HTTP::header exists "X-Frame-Options" ])} {

    HTTP::header insert "X-Frame-Options" "SAMEORIGIN"

  }

  if {!([HTTP::header exists "X-XSS-Protection"])} {

    HTTP::header insert "X-XSS-Protection" "1; mode=block"

  }

  if {!([HTTP::header exists "X-Content-Type-Options"])} {

    HTTP::header insert "X-Content-Type-Options" "nosniff"

  }

  if {!([HTTP::header exists "Strict-Transport-Security"])} {

    HTTP::header insert "Strict-Transport-Security" "max-age=16070400; includeSubDomains"

  }

  if { $insert_xframe } then {

    HTTP::header insert "X-Frame-Options" "ALLOWED"

  }

}

Would appreciate any thoughts or suggestions.

Thank you.

Chris