*
     * @return a new builder, never {@code null}
     */
    @Nonnull
    static VersionResolverRequestBuilder builder() {
        return new VersionResolverRequestBuilder();
    }

    /**
     * Builder for {@link VersionRangeResolverRequest}.
     */
    @NotThreadSafe
    class VersionResolverRequestBuilder {
        Session session;
        RequestTrace trace;