}
                throw new ExtractException("Failed to extract the content using available extractors.");
            }

            @Override
            public int getWeight() {
                return extractors[0].getWeight();
            }
        };
    }

    /**
     * Retrieves all extractors for the specified key.
     * @param key The key associated with the extractors.

    /**
     * Returns the weight of the extractor.
     * The default implementation returns a weight of 1.
     *
     * @return the weight of the extractor
     */
    default int getWeight() {
        return 1;
    }

                reader.setInput(input);
                final ImageReadParam param = reader.getDefaultReadParam();
                final int width = reader.getWidth(0);
                final int height = reader.getHeight(0);
                if (width <= 0 || height <= 0) {
                    return Result.NO_IMAGE;
                }
                if (!fessConfig.validateThumbnailSize(width, height)) {

                        // head method
                        responseData =
                                client.execute(RequestDataBuilder.newRequestData().head().url(url).weight(urlQueue.getWeight()).build());
                        if (responseData == null) {
                            return true;
                        }

      return new DummyValueReference<>();
    }

    @Override
    public V get() {
      return value;
    }

    @Override
    public int getWeight() {
      return 1;
    }

    @Override
    public @Nullable ReferenceEntry<K, V> getEntry() {
      return null;
    }

    @Override
    public ValueReference<K, V> copyFor(