@SuppressWarnings("unchecked") // Casts guarded by conditionals.
static TypeAdapter<?> getTypeAdapter(ConstructorConstructor constructorConstructor, Gson gson,
    TypeToken<?> fieldType, JsonAdapter annotation) {
  Class<?> value = annotation.value();
  if (TypeAdapter.class.isAssignableFrom(value)) {
        Class<TypeAdapter<?>> typeAdapter = (Class<TypeAdapter<?>>) value;
    return constructorConstructor.get(TypeToken.get(typeAdapter)).construct();
  }
  if (TypeAdapterFactory.class.isAssignableFrom(value)) {
        Class<TypeAdapterFactory> typeAdapterFactory = (Class<TypeAdapterFactory>) value;
    return constructorConstructor.get(TypeToken.get(typeAdapterFactory))
        .construct()
        .create(gson, fieldType);
  }

  throw new IllegalArgumentException(
      "@JsonAdapter value must be TypeAdapter or TypeAdapterFactory reference.");
}
 

@SuppressWarnings("unchecked")
@Override
public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> targetType) {
  Class<? super T> rawType = targetType.getRawType();
  JsonAdapter annotation = rawType.getAnnotation(JsonAdapter.class);
  if (annotation == null) {
    return null;
  }
  return (TypeAdapter<T>) getTypeAdapter(constructorConstructor, gson, targetType, annotation);
}
 

@SuppressWarnings({ "unchecked", "rawtypes" }) // Casts guarded by conditionals.
TypeAdapter<?> getTypeAdapter(ConstructorConstructor constructorConstructor, Gson gson,
    TypeToken<?> type, JsonAdapter annotation) {
  Object instance = constructorConstructor.get(TypeToken.get(annotation.value())).construct();

  TypeAdapter<?> typeAdapter;
  if (instance instanceof TypeAdapter) {
    typeAdapter = (TypeAdapter<?>) instance;
  } else if (instance instanceof TypeAdapterFactory) {
    typeAdapter = ((TypeAdapterFactory) instance).create(gson, type);
  } else if (instance instanceof JsonSerializer || instance instanceof JsonDeserializer) {
    JsonSerializer<?> serializer = instance instanceof JsonSerializer
        ? (JsonSerializer) instance
        : null;
    JsonDeserializer<?> deserializer = instance instanceof JsonDeserializer
        ? (JsonDeserializer) instance
        : null;
    typeAdapter = new TreeTypeAdapter(serializer, deserializer, gson, type, null);
  } else {
    throw new IllegalArgumentException("Invalid attempt to bind an instance of "
        + instance.getClass().getName() + " as a @JsonAdapter for " + type.toString()
        + ". @JsonAdapter value must be a TypeAdapter, TypeAdapterFactory,"
        + " JsonSerializer or JsonDeserializer.");
  }

  if (typeAdapter != null && annotation.nullSafe()) {
    typeAdapter = typeAdapter.nullSafe();
  }

  return typeAdapter;
}
 

@SuppressWarnings("unchecked")
public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> targetType) {
  JsonAdapter annotation = targetType.getRawType().getAnnotation(JsonAdapter.class);
  if (annotation == null) {
    return null;
  }
  return (TypeAdapter<T>) getTypeAdapter(constructorConstructor, gson, targetType, annotation);
}
 

private TypeAdapter<?> getFieldAdapter(Gson gson, Field field, TypeToken<?> fieldType) {
  JsonAdapter annotation = field.getAnnotation(JsonAdapter.class);
  if (annotation != null) {
    TypeAdapter<?> adapter = getTypeAdapter(constructorConstructor, gson, fieldType, annotation);
    if (adapter != null) return adapter;
  }
  return gson.getAdapter(fieldType);
}