My language configuration :

language = StandardLanguage {
			name = "..."
			fileExtensions = "cf_app"
			referencedResource = "platform:/resource/...model/cofluent.genmodel"
			fragment = ecore2xtext.Ecore2XtextValueConverterServiceFragment2 auto-inject {}

			fragment = org.eclipse.xtext.generator.adapter.FragmentAdapter {
				fragment = org.eclipse.xtext.generator.ecore2xtext.FormatterFragment {}
			}

			serializer = {
				generateStub = false
			}
			
			// generator API
			fragment = generator.GeneratorFragment2 {
				generateJavaMain = true
			}
		}