* @return this builder, never {@code null}
         */
        public VersionResolverRequestBuilder nature(Nature nature) {
            this.nature = Objects.requireNonNullElse(nature, Nature.RELEASE_OR_SNAPSHOT);
            return this;
        }

        /**
         * Sets the repositories to use for resolving the version range.
         *

   * lazy evaluation of the fallback instance, using {@link Optional#or(Supplier)
   * first.or(supplier)}.
   *
   * <p><b>Java 9 users:</b> use {@code java.util.Objects.requireNonNullElse(first, second)}
   * instead.
   *
   * @return {@code first} if it is non-null; otherwise {@code second} if it is non-null
   * @throws NullPointerException if both {@code first} and {@code second} are null

   * lazy evaluation of the fallback instance, using {@link Optional#or(Supplier)
   * first.or(supplier)}.
   *
   * <p><b>Java 9 users:</b> use {@code java.util.Objects.requireNonNullElse(first, second)}
   * instead.
   *
   * @return {@code first} if it is non-null; otherwise {@code second} if it is non-null
   * @throws NullPointerException if both {@code first} and {@code second} are null