* to implement the related methods as well. Finally, two collection views are provided: {@link
 * #elementSet} contains the distinct elements of the multiset "with duplicates collapsed", and
 * {@link #entrySet} is similar but contains {@link Entry Multiset.Entry} instances, each providing
 * both a distinct element and the count of that element.
 *

    } catch (IllegalArgumentException expected) {
      // We don't really care which values the exception message contains, but they should be
      // different from each other. If buildKeepingLast() collapsed duplicates, that might end up
      // not being true.
      Pattern pattern = Pattern.compile("Multiple entries with same key: four=(.*) and four=(.*)");
      assertThat(expected).hasMessageThat().matches(pattern);

   * @param isFinalPart Is this the final (rightmost) domain part?
   * @return Whether the part is valid
   */
  private static boolean validatePart(String part, boolean isFinalPart) {

    // These tests could be collapsed into one big boolean expression, but
    // they have been left as independent tests for clarity.

    if (part.length() < 1 || part.length() > MAX_DOMAIN_PART_LENGTH) {
      return false;
    }

    /*

   * an edge connecting node A to node B if this {@link Network} has an edge connecting A to B.
   *
   * <p>If this network {@link #allowsParallelEdges() allows parallel edges}, parallel edges will be
   * treated as if collapsed into a single edge. For example, the {@link #degree(Object)} of a node
   * in the {@link Graph} view may be less than the degree of the same node in this {@link Network}.
   */
  Graph<N> asGraph();

  //

    } catch (IllegalArgumentException expected) {
      // We don't really care which values the exception message contains, but they should be
      // different from each other. If buildKeepingLast() collapsed duplicates, that might end up
      // not being true.
      Pattern pattern = Pattern.compile("Multiple entries with same key: four=(.*) and four=(.*)");
      assertThat(expected).hasMessageThat().matches(pattern);

      extends TestUnhashableCollectionGenerator<Set<UnhashableObject>>
      implements TestSetGenerator<UnhashableObject> {}

  private static Ordering<String> createExplicitComparator(String[] elements) {
    // Collapse equal elements, which Ordering.explicit() doesn't support, while
    // maintaining the ordering by first occurrence.
    Set<String> elementsPlus = Sets.newLinkedHashSet();
    elementsPlus.add(BEFORE_FIRST);

    assertEquals("1.2.3.4", InetAddresses.toUriString(ip));
  }

  public void testToUriStringIPv6() {
    // Unfortunately the InetAddress.toString() method for IPv6 addresses
    // does not collapse contiguous shorts of zeroes with the :: abbreviation.
    String ipStr = "3ffe::1";
    InetAddress ip = InetAddresses.forString(ipStr);
    assertEquals("[3ffe::1]", InetAddresses.toUriString(ip));
  }

   * href="http://tools.ietf.org/html/rfc4291#section-2.5.5.2">RFC 4291</a>.
   *
   * <p>Note: This method takes a {@code String} argument because {@link InetAddress} automatically
   * collapses mapped addresses to IPv4. (It is actually possible to avoid this using one of the
   * obscure {@link Inet6Address} methods, but it would be unwise to depend on such a
   * poorly-documented feature.)
   *

          return finishCollapseFrom(sequence, i + 1, len, replacement, builder, true);
        }
      }
    }
    // no replacement needed
    return sequence.toString();
  }

  /**
   * Collapses groups of matching characters exactly as {@link #collapseFrom} does, except that
   * groups of matching BMP characters at the start or end of the sequence are removed without
   * replacement.
   */

    assertEquals("1.2.3.4", InetAddresses.toUriString(ip));
  }

  public void testToUriStringIPv6() {
    // Unfortunately the InetAddress.toString() method for IPv6 addresses
    // does not collapse contiguous shorts of zeroes with the :: abbreviation.
    String ipStr = "3ffe::1";
    InetAddress ip = InetAddresses.forString(ipStr);
    assertEquals("[3ffe::1]", InetAddresses.toUriString(ip));
  }