code: public void setSessionAttributes(Map<String, Object> sessionAttributes) {
          if (requestEnvelope.getSession() == null) {
              throw new IllegalStateException("Attempting to set session attributes for out of session request");
          }
          this.sessionAttributes = sessionAttributes;
      }
docs: Sets session attributes, replacing any existing attributes already present in the session. An exception is thrown
  if this method is called while processing an out of session request. Use this method when bulk replacing attributes
  is desired.
  
  @param sessionAttributes session attributes to set
  @throws IllegalStateException if attempting to retrieve session attributes from an out of session request