and finally, defined the meta-editor, specifying the related Velocity template
... a last one for Boolean editor
<meta-editor key="editMetaBoolean" name="Edit Meta Attribute as Boolean">
<resource type="velocity" name="edit" location="com/minyaa/workflows/templates/meta-attributes-edit-boolean.vm"/>
</meta-editor>
How to extend Meta-Attributes
To extend the list of displayed Meta-Attributes depending on the list of supported process as follow ... Use the custom plugin module-type meta-attribute