code: public static boolean hasValue(InputComponent<?, ?> input)
     {
        boolean ret;
        Object value = InputComponents.getValueFor(input);
        if (value == null)
        {
           ret = false;
        }
        else if (value instanceof String && value.toString().isEmpty())
        {
           ret = false;
        }
        else if (!input.getValueType().isInstance(value) && value instanceof Iterable
                 && !((Iterable) value).iterator().hasNext())
        {
           ret = false;
        }
        else
        {
           ret = true;
        }
        return ret;
     }
docs: Returns if there is a value set for this {@link InputComponent}