DateTimeFormatter.ISO_INSTANT: Parsing fails in ThreeTenBP but not java.time.format

[joschi]

org.threeten.bp.format.DateTimeFormatter.ISO_INSTANT seems to behave differently than java.time.format.DateTimeFormatter.ISO_INSTANT when parsing timestamps:

@Test
public void dateTimeFormatterIsoInstant() {
  assertNotNull(java.time.format.DateTimeFormatter.ISO_INSTANT.parse("2023-08-11T23:08:44.848+00:30"));
  assertNotNull(org.threeten.bp.format.DateTimeFormatter.ISO_INSTANT.parse("2023-08-11T23:08:44.848+00:30"));
}

Error message:

org.threeten.bp.format.DateTimeParseException: Text '2023-08-11T23:08:44.848+00:30' could not be parsed at index 23

	at org.threeten.bp.format.DateTimeFormatter.parseToBuilder(DateTimeFormatter.java:1588)
	at org.threeten.bp.format.DateTimeFormatter.parse(DateTimeFormatter.java:1416)

This seems to be related to https://bugs.openjdk.org/browse/JDK-8166138 which addressed the issue in Java 12.

The question is whether ThreeTenBP should be a backport of the Java 8 java.time classes or if these newer additions should also be covered.