The newly added persons have contributed code to JACK in the past.
(mentioned in at least one file header)

tests/cpu.c:    Copyright (C) 2005 Samuel TRACOL
linux/alsa/usx2y.c:    Copyright (C) 2005 Karsten Wiese, Rui Nuno Capela
linux/alsa/ice1712.h:    Copyright (C) 2000 by Jaroslav Kysela <perex@suse.cz>
example-clients/metro.c:    Copyright (C) 2002 Anthony Van Groningen
dbus/controller_iface_transport.c:    Copyright (C) 2008 Juuso Alasuutari
common/netjack.h:    Copyright (C) 2003 Robert Ham <rah@bash.sh>
common/jack/ringbuffer.h:  Copyright (C) 2003 Rohan Drape
common/jack/metadata.h:  Copyright (C) 2011 David Robillard
common/JackMidiPort.cpp:Original JACK MIDI implementation Copyright (C) 2004 Ian Esten
linux/firewire/JackFFADODriver.cpp:Copyright (C) 2012 Jonathan Woithe
common/jack/statistics.h:  Copyright (C) 2004 Rui Nuno Capela, Lee Revell

The authors list should be up-to-date now.

-Add "new" alumni authors according to jackd manpage listed under "Programming"

+Andy Wingo
+Jack O'Quin
+Jeremy Hall
+Johnny Petrantoni
+Jussi Laako
+Kai Vehmanen
+Melanie Thielker
+Steve Harris
+Taybin Rutkin
+Tilman Linneweh
+Stefan Schwandter
+Alexandre Prokoudine

-Add new authors according to https://github.com/jackaudio/jack2/graphs/contributors
-Order alphabetically by FIRST NAME (this is simple for |sort)

Karl Lindén (karllinden)
Timo Wischer (twischer-adit)
Thomas Brand (7890)
Cédric Schieli (sdrik)
Markus Seeber (mseeber)
Alba Mendez (jmendeth)
David Runge (dvzrv)
Olivier Humbert (trebmuh)
Yasuhiro Fujii (y-fujii)
Gaël Portay (gportay)
James P. Thomas (jamespthomas)
Andreas Müller (schnitzeltony)
Holger Dehnhardt (dehnhardt)
Rui Nuno Capela (rncbc)
Michał Szymański (smiszym)
Francis Pinteric (fjapinteric)
Bruno Vernay (BrunoVernay)
Hunter L. Allen (allenh1)
Edward Betts (EdwardBetts)
Thomas Petazzoni (tpetazzoni)
James Cowgill (jcowgill)
Samuel Martin (tSed)
Bernhard M. Wiedemann (bmwiedemann)
Jacek Konieczny (Jajcus)
Andrew Kelley (andrewrk)
Maks Naumov (maksqwe)
Julien Acroute (Vampouille)
Youri Westerman (4c0n)
Olaf Hering (olafhering)
Ricardo Crudo (ricardocrudo)
Maxim Grishin (Igevorse)
Valentin David (valentindavid)
Joshua Moyerman (jmoyerman)
Arnaud Rebillout (elboulangero)
Alexander Graf (agraf)
Eliot Blennerhassett (eliotb)
Deven Lahoti (dlahoti)

Not added (need more info) github handles
fps
mojofunk
e9925248
farwayer
l1n
stratakis
m-grabner
bkuhls
escitalopram