Envelope 
  class Envelope 
  A message wrapped in an envelope with items (configurations, markers, .
 ..).
   Methods
  Details
                         
    __construct(object $message, array $items = array())
         
   Parameters
   | object |  $message |   |  
  | array |  $items |   |  
 
        Wrap a message into an envelope if not already wrapped.
   Parameters
  Return Value
         Parameters
  Return Value
   | Envelope |  a new Envelope instance with additional item |  
 
                           Envelope
    withMessage($message)
         
   Parameters
  Return Value
                            EnvelopeItemInterface|null
    get(string $itemFqcn)
         
   Parameters
  Return Value
   | EnvelopeItemInterface|null |   |  
 
                           array
    all()
         
   Return Value
                            object
    getMessage()
         
   Return Value
   | object |  The original message contained in the envelope |