DateField component trims info about time from date range validation

Originally by Ellrohir

I am using two Vaadin DateFields for FROM-TO interval input from user. I naturally want TO date being after FROM date. So I put a ValueChangeListner on each that sets RangeStart/RangeEnd to each other DateField. The resolution of both DateFields is Resolution.MINUTE, because I need precision in minutes.

I have found the automatic validation does't work when user inputs TO date for the same day as FROM date, but between 00:00 and FROM input (so TO 2016-04-14 10:24 passes the test when FROM is 2016-04-15 10:25). I have tracked down the code in Vaadin and found method DateField.getRangeStart(Resolution forResolution). This method strips info about time from input, so it returns 2016-04-14 00:00 instead of 2016-04-14 10:24. Then the valiadion obviously must fail...

The reason is this part of code:

        if (forResolution == Resolution.YEAR) {
            startCal.set(startCal.get(Calendar.YEAR), 0, 1, 0, 0, 0);
        } else if (forResolution == Resolution.MONTH) {
            startCal.set(startCal.get(Calendar.YEAR),
                    startCal.get(Calendar.MONTH), 1, 0, 0, 0);
        } else {
            startCal.set(startCal.get(Calendar.YEAR),
                    startCal.get(Calendar.MONTH), startCal.get(Calendar.DATE),
                    0, 0, 0);
        }

namely the else branch

            startCal.set(startCal.get(Calendar.YEAR),
                    startCal.get(Calendar.MONTH), startCal.get(Calendar.DATE),
                    0, 0, 0);

When I have Resolution.MINUTE, the program falls into this branch and the Calendar is set to 00:00:00...then startCal.getTime() is returned and I am short of my time info...

In my code I can obviously add aditional validation. But I think this should be fixed to work properly respecting the actual Resolution of particular DateField.

I still see the same code in [https://github.com/vaadin/vaadin/blob/master/server/src/com/vaadin/ui/DateField.java] so it should be just me and my old Vaadin version.

Thanks for any feedback. I may be also wrong for some reason.

Imported from https://dev.vaadin.com/ issue #19739

Start in server/src/com/vaadin/ui/DateField.java at getRangeStart(Resolution forResolution), focusing on the else branch shown in the issue. Verify how Resolution.MINUTE is handled and confirm the range validation preserves the entered time; the issue is done when same-day FROM and TO values are validated by their actual minute-level ordering.