The WildFly snapshot for 9.0.0.Alpha1 submits the serious warning below, when PicketLink is used. This warning is a result of upgrading to Weld 2.2.4. Please make the fix (at the bottom) before releasing WFLY 9. Thank you.
The fix is:
In file feature-pack/src/main/resources/modules/system/layers/base/org/picketlink/core/main/module.xml add these two lines within the <dependencies> block: