5.1 EE SP4 (5.1.7), 5.2 EE SP2 (5.2.6)
If you try to override it through a plugin hook, you will get an exception.
Note: this class has been changed to an interface. The implementation can be found in DefaultScreenNameValidator
In portal-ext.properties, if you have
this line must be changed to
- is related to
LPS-6601 Unable to override ScreenNameValidator through hooks