DurationFormatterUtils should not attempt to parse an empty duration

[Seungpang]

Hi Team,

While testing the DurationFormatterUtils functionality, I came across a couple of issues that I'd like to address in this PR

1. Empty String Handling in parse Method:

   • Currently, when an empty string ("", " ") is passed to the parseComposite(value) method, the result is PT0S instead of an exception being thrown. This doesn't seem like the correct behavior, as an empty string is an invalid input and returning PT0S can be misleading in this case.

2. NullPointerException (NPE) in print Method:

   • The print method does not handle null values properly for the Duration parameter, resulting in a NullPointerException.

Changes

• parse method:
  • Added validation for empty strings and null values.
• print method:
  • Added validation for null Duration values.
• Changed error handling to throw Exception instead of Throwable

Thank you for taking the time to review this PR! Please feel free to share any feedback or suggestions.

[snicoll]

@Seungpang thanks for the PR. I've reverted the change on the print method as the current behavior is expected, considering that Duration is flagged as mandatory.