code: public boolean isCollapsed() {
          boolean v = JQMCommon.hasStyle(this, "ui-collapsible-collapsed");
          if (v) return v;
          if (!isInstance(getElement())) {
              String s = getAttribute("data-collapsed");
              if (Empty.is(s)) return true; // true by default, see https://api.jquerymobile.com/collapsible/#option-collapsed
              if ("false".equalsIgnoreCase(s)) return false;
              else return true;
          }
          return false;
      }
docs: Returns true if this {@link JQMCollapsible} is currently collapsed.