}

  private static final class NullFriendlyComparator<T> implements Comparator<T>, Serializable {
    @Override
    public int compare(T left, T right) {
      return String.valueOf(left).compareTo(String.valueOf(right));
    }
  }

                      public int compare(Entry<String, String> left, Entry<String, String> right) {
                        return ComparisonChain.start()
                            .compare(left.getKey(), right.getKey(), Ordering.natural().nullsFirst())
                            .compare(
                                left.getValue(), right.getValue(), Ordering.natural().nullsFirst())
                            .result();

    }

    private void assertVersionOlder(String left, String right) {
        assertTrue(
                newArtifactVersion(left).compareTo(newArtifactVersion(right)) < 0,
                left + " should be older than " + right);
        assertTrue(
                newArtifactVersion(right).compareTo(newArtifactVersion(left)) > 0,
                right + " should be newer than " + left);
    }

  }

  @Override
  public int compare(@CheckForNull T left, @CheckForNull T right) {
    if (left == right) {
      return 0;
    }
    if (left == null) {
      return RIGHT_IS_GREATER;
    }
    if (right == null) {
      return LEFT_IS_GREATER;
    }
    return ordering.compare(left, right);
  }

  @Override

   *   <li>When the RateLimiter is not used, this goes right (up to maxPermits)
   *   <li>When the RateLimiter is used, this goes left (down to zero), since if we have
   *       storedPermits, we serve from those first
   *   <li>When _unused_, we go right at a constant rate! The rate at which we move to the right is
   *       chosen as maxPermits / warmupPeriod. This ensures that the time it takes to go from 0 to

      return new Ordering<Entry<String, Integer>>() {
        @Override
        public int compare(Entry<String, Integer> left, Entry<String, Integer> right) {
          return left.getKey().compareTo(right.getKey());
        }
      }.sortedCopy(insertionOrder);
    }

    @Override
    public List<Entry<String, Integer>> create(Object... elements) {

        new Comparator<NonComparableSuperClass>() {
          @Override
          public int compare(NonComparableSuperClass left, NonComparableSuperClass right) {
            return left.value.compareTo(right.value);
          }
        };

    MutableGraph<NonComparableSuperClass> graph =
        GraphBuilder.undirected().nodeOrder(ElementOrder.sorted(comparator)).build();

      return asList(all).subList(2, elements.length + 2);
    }
  }

  private static Float[] concat(Float[] left, Float[] right) {
    Float[] result = new Float[left.length + right.length];
    System.arraycopy(left, 0, result, 0, left.length);
    System.arraycopy(right, 0, result, left.length, right.length);
    return result;
  }

  public abstract static class TestFloatListGenerator implements TestListGenerator<Float> {

      return asList(all).subList(2, elements.length + 2);
    }
  }

  private static Long[] concat(Long[] left, Long[] right) {
    Long[] result = new Long[left.length + right.length];
    System.arraycopy(left, 0, result, 0, left.length);
    System.arraycopy(right, 0, result, left.length, right.length);
    return result;
  }

  public abstract static class TestLongListGenerator implements TestListGenerator<Long> {

  }

  private static final class NullFriendlyComparator<T> implements Comparator<T>, Serializable {
    @Override
    public int compare(T left, T right) {
      return String.valueOf(left).compareTo(String.valueOf(right));
    }
  }