code: protected void sendBroadcast(Set<String> sessionIds) {
  
          if (sessionIds == null) {
              OpenCms.getSessionManager().sendBroadcast(
                  A_CmsUI.getCmsObject(),
                  m_message.getValue(),
                  m_repeat.getValue().booleanValue());
              USER_BROADCAST.put(
                  A_CmsUI.getCmsObject().getRequestContext().getCurrentUser(),
                  new CmsBroadcast(
                      A_CmsUI.getCmsObject().getRequestContext().getCurrentUser(),
                      m_message.getValue(),
                      m_repeat.getValue().booleanValue()));
          } else {
              for (String id : sessionIds) {
                  OpenCms.getSessionManager().sendBroadcast(
                      A_CmsUI.getCmsObject(),
                      m_message.getValue(),
                      id,
                      m_repeat.getValue().booleanValue());
              }
          }
      }
docs: Sends broadcast.<p>
  
  @param sessionIds to send broadcast to