title: List of parameter of request.getHeader(String value)
body: <p>I need the list of String parameter of <strong>request.getHeader(String value)</strong> .
  I already know one which is "User-Agent" (e.g. request.getHeader("User-Agent") )</p>
  
  <p>also for such cases about other methods like this, how do I get the list of parameter of such methods.</p>