In the org.wildfly.arquillian:wildfly-testing-tools there is a DeploymentDescriptor helper which allows creating a permissions.xml file. It would be useful to have a utility that also allows appending to an existing permissions.xml file.

Duplicates should not be allowed. A duplicate is a permission of the same type with the same name and actions. For example if a PropertyPermission has a different action, e.g. read vs read,write, the properties should be considered not equal and both should be in the permissions.xml file.