Property<String> getSomeProperty()
}

abstract class DefaultNewThing implements NewThing {
    // special logic to integrate with something existing
}
```

or

```groovy
public abstract class NewThing {
    public abstract Property<String> getSomeProperty()
    // special logic to integrate with something existing
}
```

This is not acceptable:

```groovy
public interface NewThing {

    }

    @Override
    public SortedMultiset<E> descendingMultiset() {
      return new StandardDescendingMultiset() {

        @Override
        Iterator<Entry<E>> entryIterator() {
          return backingMultiset.descendingMultiset().entrySet().iterator();
        }
      };
    }

    @Override
    public NavigableSet<E> elementSet() {
      return new StandardElementSet();
    }

    @Override

    StringSubscriber s2 = new StringSubscriber();
    ObjectSubscriber o1 = new ObjectSubscriber();

    Iterator<Subscriber> empty = registry.getSubscribers("");
    assertFalse(empty.hasNext());

    empty = registry.getSubscribers("");

    registry.register(s1);
    assertFalse(empty.hasNext());

    Iterator<Subscriber> one = registry.getSubscribers("");
    assertEquals(s1, one.next().target);

                  public int size() {
                    return deduped.length;
                  }

                  @Override
                  public Iterator<String> iterator() {
                    return MinimalCollection.of(deduped).iterator();
                  }
                };
              }
            })
        .named("AbstractSet")
        .withFeatures(
            CollectionFeature.NONE,

  }

  public void testIteratorPastEndException() {
    MinMaxPriorityQueue<Integer> mmHeap = MinMaxPriorityQueue.create();
    mmHeap.addAll(Lists.newArrayList(1, 2));
    Iterator<Integer> it = mmHeap.iterator();
    assertTrue("Iterator has reached end prematurely", it.hasNext());
    it.next();
    it.next();
    assertThrows(NoSuchElementException.class, () -> it.next());
  }

    return adjacentNodes();
  }

  @Override
  public Set<N> successors() {
    return adjacentNodes();
  }

  @Override
  public Iterator<EndpointPair<N>> incidentEdgeIterator(N thisNode) {
    return Iterators.transform(
        adjacentNodeValues.keySet().iterator(),
        (N incidentNode) -> EndpointPair.unordered(thisNode, incidentNode));
  }

  @Override
  public @Nullable V value(N node) {

      return standardSetCount(element, count);
    }

    @Override
    public Set<T> elementSet() {
      return new StandardElementSet();
    }

    @Override
    public Iterator<T> iterator() {
      return standardIterator();
    }

    @Override
    public boolean isEmpty() {
      return standardIsEmpty();
    }

    @Override
    public int size() {

  static final LegacyComparable Y = new LegacyComparable("y");
  static final LegacyComparable Z = new LegacyComparable("z");

  static final Iterable<LegacyComparable> VALUES_FORWARD = asList(X, Y, Z);
  static final Iterable<LegacyComparable> VALUES_BACKWARD = asList(Z, Y, X);

  private final String value;

  LegacyComparable(String value) {
    this.value = value;
  }

  @Override

                new TestStringSetGenerator() {
                  @Override
                  protected Set<String> create(String[] elements) {
                    Iterable<String> rowKeys = ImmutableSet.copyOf(elements);
                    Iterable<Integer> columnKeys = ImmutableList.of(1, 2, 3);
                    Table<String, Integer, Character> table =
                        ArrayTable.create(rowKeys, columnKeys);

            putAll(map);
        }
    }

    @Override
    public String toString() {
        StringBuilder buffer = new StringBuilder("ManagedVersionMap (" + size() + " entries)\n");
        Iterator<String> iter = keySet().iterator();
        while (iter.hasNext()) {
            String key = iter.next();
            buffer.append(key).append('=').append(get(key));
            if (iter.hasNext()) {
                buffer.append('\n');