code: public static void showMessageCenter(final Context context, final BooleanCallback callback, final Map<String, Object> customData) {
  		dispatchConversationTask(new ConversationDispatchTask(callback, DispatchQueue.mainQueue()) {
  			@Override
  			protected boolean execute(Conversation conversation) {
  				return ApptentiveInternal.getInstance().showMessageCenterInternal(context, customData);
  			}
  		}, "show message center");
  	}
docs: Opens the Apptentive Message Center UI Activity, and allows custom data to be sent with the
  next message the user sends. If the user sends multiple messages, this data will only be sent
  with the first message sent after this method is invoked. Additional invocations of this method
  with custom data will repeat this process. If Message Center is closed without a message being
  sent, the custom data is cleared. This task is performed asynchronously. Message Center
  configuration may not have been downloaded yet when this is called.
  
  @param context    The context from which to launch the Message Center. This should be an
  Activity, except in rare cases where you don't have access to one, in which
  case Apptentive Message Center will launch in a new task.
  @param callback   Called after we check to see if Message Center can be displayed, but before
  it is displayed. Called with true if an Interaction will be displayed, else
  false.
  @param customData A Map of String keys to Object values. Objects may be Strings, Numbers, or
  Booleans. If any message is sent by the Person, this data is sent with it,
  and then cleared. If no message is sent, this data is discarded.