Allowing conversion of RFC3339 dates with date part only (yyyy-MM-dd) as per HTML5 and w3 standard for <input type="date" /> (and others).

Facts:

• <input type="date" />

  is the HTML5 standard for inputing dates. It works in many browsers: Chrome, Opera, almost every mobile browsers - where it is fundamental - and the coverage can only grow.

• w3 has chosen the RFC3339 with date only as value format

  yyyy-MM-dd

  while transparently handling the display format according to the Locale.
  This means that, for example, americans see

  MM/dd/yyyy

  , italians see

  dd/MM/yyyy

  , but both of them send

  yyyy-MM-dd

  to the server. Without the time part.

• Struts Date Converter already works for:
  DateConverter.java

  DateFormat dt1 = DateFormat.getDateTimeInstance(DateFormat.SHORT, DateFormat.LONG, locale);
  DateFormat dt2 = DateFormat.getDateTimeInstance(DateFormat.SHORT, DateFormat.MEDIUM, locale);
  DateFormat dt3 = DateFormat.getDateTimeInstance(DateFormat.SHORT, DateFormat.SHORT, locale);
  
  DateFormat d1 = DateFormat.getDateInstance(DateFormat.SHORT, locale);
  DateFormat d2 = DateFormat.getDateInstance(DateFormat.MEDIUM, locale);
  DateFormat d3 = DateFormat.getDateInstance(DateFormat.LONG, locale);
  
  DateFormat rfc3339 = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss");
  

  with a final fallback to

  DateFormat.SHORT

  if nothing worked (in case of Time and Timestamps too).

My idea is:

can we add the support for date-only RFC3339, that is the one sent by the browser, in addition to the ones already there ? No existing code would break, and we'd have a standard, automatic conversion for a popular, growing standard.

I can't see any cons. Can you ?