*
         * @param rootArtifact the root artifact for the dependency graph, may be {@code null}
         * @return this request for chaining, never {@code null}
         */
        @Nonnull
        public DependencyResolverRequestBuilder rootArtifact(@Nullable Artifact rootArtifact) {
            this.rootArtifact = rootArtifact;
            return this;
        }

        /**