@Nullable
    @Override
    default <T> T as(Class<T> type) {
        return Unwrappable.super.as(type);
    }
Undecorates this {@link Backoff} to find the {@link Backoff} which is an instance of the specified
{@code type}.

@param type the type of the desired {@link Backoff}
@return the {@link Backoff} which is an instance of {@code type} if this {@link Backoff}
        decorated such a {@link Backoff}, or {@code null} otherwise.

@see Unwrappable
core/src/main/java/com/linecorp/armeria/client/retry/Backoff.java