As a reward to the "handing over" of Pakistan's ISI-protected terror operatives.
China is Pakistan's No.1 ally, by the way.
Well for the facts-as Pakistan is getting 20 odd F-16s,it will get nearly 150 Chinese built FC-1 fighters(specially developed for Pakistan),4 frigates,tanks.....The 2 nations have recently finished the first part of a joint deep water port,on Pakistan's coastline near Iran-which could complicate matters when China seeks to project power.
The new F-16s,if they are block 50/52s with new toys could be of interest to the PLAAF.Afterall there is plenty of suspicion that Pakistan handed over an F-16 or 2 to China in early 90s/late 80s which helped in part to develop new aircraft like the FC-1 & the J-10.