private void warnAboutIncompatibleStyles() {
      report().annotationNamed(StyleMirror.simpleName())
          .warning(About.INCOMPAT,
              "Use styles only on enclosing types."
                  + " All nested styles will inherit it."
                  + " Nested immutables cannot deviate in style from enclosing type,"
                  + " so generated stucture will be consistent");
    }
Element used mostly for error reporting,
real model provided by {@link #sourceElement()}.
value-processor/src/org/immutables/value/processor/meta/Proto.java