To trigger the generation of the jboss-app.xml file you need to configure the 'jboss' element. For instance to target version 4 of JBoss with a 'guest' unauthenticated principal and a scoped classloader:
<build> <plugins> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-ear-plugin</artifactId> <version>3.1.0</version> <configuration> [...] <jboss> <version>4</version> <unauthenticated-principal>guest</unauthenticated-principal> <loader-repository>com.foo:loader=foo-application-1.0.ear</loader-repository> </jboss> </configuration> </plugin> </plugins> </build>