* If {@code null} is provided, defaults to {@link Nature#RELEASE_OR_SNAPSHOT}.
         *
         * @param nature the repository nature, or {@code null} to use the default
         * @return this builder, never {@code null}
         */
        public VersionResolverRequestBuilder nature(Nature nature) {
            this.nature = Objects.requireNonNullElse(nature, Nature.RELEASE_OR_SNAPSHOT);
            return this;
        }

     * It may contain following string values:
     * <ul>
     *     <li>"auto" - decision done based on range being resolver: if any boundary is snapshot, use "release_or_snapshot", otherwise "release"</li>
     *     <li>"release_or_snapshot" - the default</li>
     *     <li>"release" - query only release repositories to discover versions</li>
     *     <li>"snapshot" - query only snapshot repositories to discover versions</li>

                    if (lowerArtifact != null && lowerArtifact.isSnapshot()
                            || upperArtifact != null && upperArtifact.isSnapshot()) {
                        wantedNature = Metadata.Nature.RELEASE_OR_SNAPSHOT;
                    } else {
                        wantedNature = Metadata.Nature.RELEASE;
                    }
                } else {