code: public boolean containsHttpHeaders(
        java.lang.String key) {
      if (key == null) { throw new java.lang.NullPointerException(); }
      return internalGetHttpHeaders().getMap().containsKey(key);
    }
docs: <pre>
  HTTP headers to use for all responses from these URLs.
  </pre>
  
  <code>map&lt;string, string&gt; http_headers = 3;</code>