title: How to generically wrap a Rejection with Akka-Http
body: <p>I would like to use the Akka Http routing system, along with its rejection system but need to nest the response Json for a rejection within a generic Json message block.</p>
  
  <p>I have this working in a very non-generic manner creating a RejectionHandler then adding cases for all possible rejections and handling them all with the specific response code and message.  </p>
  
  <p>example:</p>
  
  <pre><code>    // Wraps string into control block format
  def WrappingBlock(msg: String) = ???
  
  val myRejectionHandler = RejectionHandler
  .newBuilder()
  .handle{case MalformedRequestContentRejection(msg, detail) =&gt;
            complete(BadRequest, WrappingBlock(msg)) }
  ...     // Further lines for all other possible rejections
  ...     // along with their response codes and messages.
  ...     // It would be nice if this was just generic code 
  ...     // rather than specific to every rejection type.
  .result()
  
  
  val routes = handleRejections(myRejectionHandler){ 
      ...
  }
  </code></pre>
  
  <p>However, what I would like is the response code that Akka HTTP provides by default and also the pretty print message that is provided, just nested within a Json control wrapper without a line for every possible rejection type.  This seems like it should be possible but I have not been able to complete it.</p>