static ImmutableMap<String, AnnotationValue> simplifyAnnotationValueMap(
      Map<? extends ExecutableElement, ? extends AnnotationValue> annotationValueMap) {
    ImmutableMap.Builder<String, AnnotationValue> builder = ImmutableMap.builder();
    for (Entry<? extends ExecutableElement, ? extends AnnotationValue> entry :
        annotationValueMap.entrySet()) {
      builder.put(entry.getKey().getSimpleName().toString(), entry.getValue());
    }
    return builder.build();
  }
Returns an annotation value map with {@link String} keys instead of {@link ExecutableElement}
instances.
factory/src/main/java/com/google/auto/factory/processor/Mirrors.java