Usage of this Regular Expression Field Validator is no more required since validation is done now by the CustomField itself.
This Validator is able to scan all fields defined in the current Screen (Create, Edit or Workflow Transition).
And it evaluate the respect of Regular Expression for Field based RegExpCFType.
n/c
The Validator configuration may be done in XML in Workflow descriptor as follow :
<validators> <validator name="" type="class"> <arg name="class.name">com.atlassian.jira.workflow.validator.RegExpCustomFieldValidator</arg> </validator> </validators>