code: @Override
      public boolean isSimple() {
          for (int i = 0; i < list.size(); i++)
              if (list.get(i).getValue() instanceof JSONComposite)
                  return false;
          return true;
      }
docs: Test whether the composite is "simple", i.e.&nbsp;it contains only non-composite values
  (to assist with formatting).
  
  @return  {@code true} if the composite is simple
  @see     JSONComposite#isSimple()