SimpleDateFormat can not parse date anymore

A DESCRIPTION OF THE PROBLEM :
JDK16+25 cannot parse a simple date:

See: https://travis-ci.org/github/graphhopper/graphhopper/jobs/744890249

REGRESSION : Last worked in version 16

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
no error
ACTUAL -
ParseException at java.base/java.text.DateFormat.parse(DateFormat.java:396)

---------- BEGIN SOURCE ----------
DateFormat df = new SimpleDateFormat("yyyy MMM dd", Locale.UK);
df.setTimeZone(TimeZone.getTimeZone("UTC"));
df.parse("2015 Sep 30"); // => java.text.ParseException: Unparseable date: "2015 Sep 30"
---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
This does not happen with JDK16+24: https://travis-ci.org/github/graphhopper/graphhopper/jobs/744725038