code: public int createConversation(String subject, String text,
  			List<Integer> participants, Reference reference) {
  		WebResource resource;
  		if (reference != null) {
  			resource = getResourceFactory().getApiResource(
  					"/conversation/" + reference.toURLFragment());
  		} else {
  			resource = getResourceFactory().getApiResource("/conversation/");
  		}
  
  		return resource
  				.entity(new ConversationCreate(subject, text, participants),
  						MediaType.APPLICATION_JSON_TYPE)
  				.post(ConversationCreateResponse.class).getConversationId();
  	}
docs: Creates a new conversation with a list of users. Once a conversation is
  started, the participants cannot (yet) be changed.
  
  @param subject
  The subject of the conversation
  @param text
  The text of the first message in the conversation
  @param participants
  List of participants in the conversation (not including the
  sender)
  @param reference
  The object the conversation should be created on, if any
  @return The id of the newly created conversation