Use lowercase name for groups when adding the to Application.groovy

griffon create-mvc Foo

    // MVC Group for "Foo"
    'Foo' {
        model      = 'foo.FooModel'
        view       = 'foo.FooView'
        controller = 'foo.FooController'
    }

griffon create-mvc bar

    // MVC Group for "bar"
    'bar' {
        model      = 'foo.BarModel'
        view       = 'foo.BarView'
        controller = 'foo.BarController'
    }