if one has an ezdatetime as Required, no content can be created using 00:00 as the time part.

Steps to reproduce:

• create a custom Content Type
• add an ezdatetime, marked as Required with Empty as default value
• attempt to create content, setting the value as 1/1/1990 00:00 (for instance)
  => Publishing operation will fail with the following error message

  {
      "ErrorMessage": {
          "_media-type": "application\/vnd.ez.api.ErrorMessage+json",
          "errorCode": 400,
          "errorMessage": "Bad Request",
          "errorDescription": "Value for required field definition 'my_date_time_field' with language 'eng-GB' is empty",
  ....
      }
  }
  

The same problems happens on Time fields (actually that's even worse because the kernel also has a bug on handling this case)

Also the display of empty Time and date and Time fields must be fixed (as explained in EZP-25270).

• Create a ContentType with a "Time" a "Date and Time" field.
• Create a new content based on this content type.
• As time use 00:00
• As dateandtime use 01/01/1970 00:00 on UTC time. So consider your timezone while entering, for example on my timezone (France in daylight saving time) I had to enter 01/01/1970 01:00