private static boolean isNullable(AnnotationMirror annotation) {
    TypeElement annotationType = MoreElements.asType(annotation.getAnnotationType().asElement());
    return annotationType.getSimpleName().contentEquals("Nullable")
        || annotationType
            .getQualifiedName()
            .toString()
            // For NullableDecl and NullableType compatibility annotations
            .startsWith("org.checkerframework.checker.nullness.compatqual.Nullable");
  }
Annotations on the parameter (not its type).
factory/src/main/java/com/google/auto/factory/processor/Parameter.java