Here is the SB Nation roster summary for the Hawks:
Jordan Williams - F/C - 6-foot-9, 247
Acquired from the Brooklyn Nets as part of the Joe Johnson trade and is expected to be added to the summer league roster at some point. Was drafted in the second round of the 2011 draft by the Nets after a two-year stay at Maryland. Williams averaged 16.9 points and 11.8 rebounds in his final year with the Terps. The Nets assigned him for a six-game stint in the D-League at Springfield where he averaged 10.8 points and 7.8 boards in 2012. He also appeared in 43 games for the Nets averaging 14.8 minutes a night. Will be one of the most experienced players on the Hawks roster.
(That's one of the most experienced players on the Hawks' summer league roster.)