Add nullability annotations for j.u.regex.Matcher and Pattern.

The only noteworthy thing here is that, although Matcher.group(int)
can return null for arguments >= 1, but Matcher.group() which
delegates to group(0) cannot return null. This is because the methods
throw unless there was a successful match, and group() returns the
whole matching substring (which may be empty, but won't be null).

Bug: 64930165
Test: make core-current-stubs-nullability-validation-check-nullability-warnings
Change-Id: I7e58d5f6f0f0139c3a24b5216bd1c82ad05758a3

0 files changed, 0 insertions, 0 deletions