private String equalsParameterType() {
    // Unlike AutoValue, we don't currently try to guess a @Nullable based on the methods in your
    // class. It's the default one or nothing.
    ImmutableList<AnnotationMirror> equalsParameterAnnotations =
        Nullables.fromMethods(processingEnv, ImmutableList.of()).nullableTypeAnnotations();
    return TypeEncoder.encodeWithAnnotations(javaLangObject, equalsParameterAnnotations);
  }
Issue a compilation error and return an exception that, when thrown, will cause the processing
of this class to be abandoned. This does not prevent the processing of other classes.
value/src/main/java/com/google/auto/value/processor/AutoAnnotationProcessor.java