This is what shows up in 1.9:  I know that this project is pretty old, but it would be great if this could be fixed.
Activity
Flawd commentedon Apr 23, 2016
I have made a fix for that (probably bad code), if you want I can send you.
Mrtenz commentedon Apr 24, 2016
That would be great.
Flawd commentedon Apr 28, 2016
http://pastebin.com/8xHHVgfX
and this is a code example of how im using it
dont know if you can still apply it to all slots
MrPowerGamerBR commentedon Jun 25, 2016
@Flawd could you reupload your code? Pastebin says the paste has expired :(
Flawd commentedon Jun 26, 2016
I dont have it anymore, sorry.
Just use this, it's better:
https://www.spigotmc.org/resources/item-attribute-modifier-api-library.22747/
MrPowerGamerBR commentedon Oct 27, 2016
Okay I finally found a solution for that bug.
That's it.