* <a href="https://github.com/google/guava/wiki/CollectionUtilitiesExplained#comparators">{@code
   * Comparators}</a>.
   *
   * @param a first value to compare, returned if less than or equal to b.
   * @param b second value to compare.
   * @throws ClassCastException if the parameters are not <i>mutually comparable</i>.
   * @since 30.0
   */
  public static <T extends Comparable<? super T>> T min(T a, T b) {

  }

  /**
   * Returns an unmodifiable view of the difference of two multisets. In the returned multiset, the
   * count of each element is the result of the <i>zero-truncated subtraction</i> of its count in
   * the second multiset from its count in the first multiset, with elements that would have a count
   * of 0 not included. The iteration order of the returned multiset matches that of the element set

  /**
   * Returns an immutable collection of all key-value pairs in the multimap. Its iterator traverses
   * the values for the first key, the values for the second key, and so on.
   */
  @Override
  public ImmutableSet<Entry<K, V>> entries() {
    ImmutableSet<Entry<K, V>> result = entries;
    return result == null ? (entries = new EntrySet<>(this)) : result;
  }

     *
     * @param first the first version.
     * @param second the second version.
     * @return negative if the first version is newer than the second version, zero if they are the same or positive if
     * the second version is the newer.
     */
    private static int compareModelVersions(String first, String second) {
        // we use a dedicated comparator because we control our model version scheme.