8136583: Core libraries should use blessed modifier order
Summary: Run blessed-modifier-order script (see bug)
Reviewed-by: psandoz, chegar, alanb, plevart

8054221: StringJoiner imlementation optimization
Reviewed-by: martin

8020977: StringJoiner merges with itself not as expected
Reviewed-by: psandoz, chegar, mduigou, smarks

8017231: Add StringJoiner.merge
Reviewed-by: psandoz, alanb
Contributed-by: brian.goetz@oracle.com, henry.jen@oracle.com