Gradle builds don't incorporate plugins

[swalton00]

If I build Griffon 16.0 with Gradle (even new archetype) with groovy and swing on Windows with Java 8, when plugins are requested in the build.gradle file, it builds successfully and most plugins run clean, but the functionality for the plugin is missing. Two examples:

1. Add in the JMX (monitor) plugin. This should require no additional configuration and a JConsole should show Griffon when connected. The Griffon data is missing (building with Griffon 15.1 with Maven and it runs correctly).
2. Add in the Datasource plugin. The compile runs successfully and the code runs successfully with no no errors. It should fail at runtime because of the missing DataSource.groovy file.