@GwtCompatible
@NullUnmarked
public class ConverterTest extends TestCase {

  private static final Converter<String, Long> STR_TO_LONG =
      new Converter<String, Long>() {
        @Override
        protected Long doForward(String object) {
          return Long.valueOf(object);
        }

        @Override
        protected String doBackward(Long object) {
          return String.valueOf(object);
        }

        @Override

 * <i>missing</i> information and the other is not. The {@link #convert} method handles this null
 * behavior for all converters; implementations of {@link #doForward} and {@link #doBackward} are
 * guaranteed to never be passed {@code null}, and must never return {@code null}.
 *
 * <h3>Common ways to use</h3>
 *
 * <p>Getting a converter:
 *
 * <ul>

      implements Serializable {

    private final Class<T> enumClass;

    StringConverter(Class<T> enumClass) {
      this.enumClass = checkNotNull(enumClass);
    }

    @Override
    protected T doForward(String value) {
      return Enum.valueOf(enumClass, value);
    }

    @Override
    protected String doBackward(T enumValue) {
      return enumValue.name();
    }

    @Override

  private static final class ShortConverter extends Converter<String, Short>
      implements Serializable {
    static final Converter<String, Short> INSTANCE = new ShortConverter();

    @Override
    protected Short doForward(String value) {
      return Short.decode(value);
    }

    @Override
    protected String doBackward(Short value) {
      return value.toString();
    }

    @Override

  private static final class ShortConverter extends Converter<String, Short>
      implements Serializable {
    static final Converter<String, Short> INSTANCE = new ShortConverter();

    @Override
    protected Short doForward(String value) {
      return Short.decode(value);
    }

    @Override
    protected String doBackward(Short value) {
      return value.toString();
    }

    @Override

      implements Serializable {
    static final Converter<String, Integer> INSTANCE = new IntConverter();

    @Override
    protected Integer doForward(String value) {
      return Integer.decode(value);
    }

    @Override
    protected String doBackward(Integer value) {
      return value.toString();
    }

    @Override

    return null;
  }

  private <F, T> Converter<F, T> defaultConverter(
      TypeToken<F> convertFromType, TypeToken<T> convertToType) {
    return new Converter<F, T>() {
      @Override
      protected T doForward(F a) {
        return doConvert(convertToType);
      }

      @Override
      protected F doBackward(T b) {
        return doConvert(convertFromType);
      }

  private static final class FloatConverter extends Converter<String, Float>
      implements Serializable {
    static final Converter<String, Float> INSTANCE = new FloatConverter();

    @Override
    protected Float doForward(String value) {
      return Float.valueOf(value);
    }

    @Override
    protected String doBackward(Float value) {
      return value.toString();
    }

    @Override

  }

  private static final class LongConverter extends Converter<String, Long> implements Serializable {
    static final Converter<String, Long> INSTANCE = new LongConverter();

    @Override
    protected Long doForward(String value) {
      return Long.decode(value);
    }

    @Override
    protected String doBackward(Long value) {
      return value.toString();
    }

    @Override

      implements Serializable {
    static final Converter<String, Double> INSTANCE = new DoubleConverter();

    @Override
    protected Double doForward(String value) {
      return Double.valueOf(value);
    }

    @Override
    protected String doBackward(Double value) {
      return value.toString();
    }

    @Override