code: @Override
      public void setContainerId(String containerId) {
          if (getId() == null) {
              super.setContainerId(containerId);
              JQMContext.attachAndEnhance(this);
          } else if (! containerId.equals(getId())) {
              throw new IllegalStateException("Attempt to change JQMPage with containerId '" + getId() + "' to '" + containerId + "' failed - once set, it cannot be changed.");
          }
      }
docs: Sets the containerId so it can be referenced by name. This can only be set once. All subsequent attempts on this
  instance will result in an IllegalStateException.
  @param containerId