Extensions validation error in Respository Application

Xwiki version: 12.5.1+2

Extension Repository Server error (attached): 

In menu to Repositories with extensions -> Actions -> Validate extensions

I really don't know if in what version it appears, i noticed it with version 12.5.1+2

Discussion link: https://forum.xwiki.org/t/dashboard-activities-problem-after-12-5-1-1/7160/19