Merge

8220585: Incorrect code in MulticastSocket sample code Summary: Sample code shows that String.length() can be passed to a DatagramPacket along with String.getBytes(), but is incorrect for non-ASCII Strings. Reviewed-by: martin, chegar Contributed-by: aeubanks@google.com

8220546: Shenandoah Reports timing details for weak root processing Reviewed-by: rkennke

8220496: Race in java_lang_String::length() when deduplicating Reviewed-by: rkennke, pliden