Entry<TypeVariable<?>, Type> entry = it.next();
        assertThat(entry.getKey().getName(), is("T1"));
        assertThat(entry.getValue(), is(sameClass(Integer.class)));
        entry = it.next();
        assertThat(entry.getKey().getName(), is("T2"));
        assertThat(entry.getValue(), is(sameClass(Long.class)));
        entry = it.next();
        assertThat(entry.getKey().getName(), is("T1"));

    assertThrows(
        ConcurrentModificationException.class,
        () -> {
          Iterator<Entry<K, V>> iterator = getMap().entrySet().iterator();
          put(e3());
          iterator.next();
        });
  }

  @MapFeature.Require({FAILS_FAST_ON_CONCURRENT_MODIFICATION, SUPPORTS_PUT})
  @CollectionSize.Require(absent = ZERO)
  public void testPutAbsentConcurrentWithKeySetIteration() {
    assertThrows(

    assertEquals(mapEntry(k0(), v0()), iterator.next());
    iterator.remove();
    assertTrue(multimap().isEmpty());
  }

  @CollectionSize.Require(absent = ZERO)
  @MapFeature.Require(SUPPORTS_REMOVE)
  public void testEntriesRemainValidAfterRemove() {
    Iterator<Entry<K, V>> iterator = multimap().entries().iterator();
    Entry<K, V> entry = iterator.next();
    K key = entry.getKey();

    assertThrows(
        ConcurrentModificationException.class,
        () -> {
          Iterator<E> iterator = collection.iterator();
          assertTrue(collection.remove(e0()));
          iterator.next();
        });
  }

  @CollectionFeature.Require(SUPPORTS_REMOVE)
  public void testRemove_notPresent() {
    assertFalse("remove(notPresent) should return false", collection.remove(e3()));
    expectUnchanged();

): List<T> {
  val ia = a.iterator()
  val ib = b.iterator()

  return buildList {
    while (ia.hasNext() || ib.hasNext()) {
      if (ia.hasNext()) {
        add(ia.next())
      }
      if (ib.hasNext()) {
        add(ib.next())
      }
    }
  }

The only new thing is the `callbacks=invoices_callback_router.routes` as an argument to the *path operation decorator*. We'll see what that is next.

## Documenting the callback { #documenting-the-callback }

The actual callback code will depend heavily on your own API app.

And it will probably vary a lot from one app to the next.

It could be just one or two lines of code, like:

```Python
callback_url = "https://example.com/api/v1/invoices/events/"

                final DfsReferral start = dr;
                do {
                    final String domain = dr.server.toLowerCase();
                    entry.map.put(domain, new HashMap());
                    dr = dr.next;
                } while (dr != start);

                _domains = entry;
                return _domains.map;
            }
        } catch (final IOException ioe) {
            if (LogStream.level >= 3) {

    multiset.add(multiset, 2);
    Multiset<Multiset<?>> copy = SerializableTester.reserialize(multiset);
    assertEquals(2, copy.size());
    assertSame(copy, copy.iterator().next());
  }

  @J2ktIncompatible
  @GwtIncompatible // Only used by @GwtIncompatible code
  private static class MultisetHolder implements Serializable {
    private final Multiset<?> member;

      @Override
      public boolean hasNext() {
        return entryItr.hasNext();
      }

      @Override
      public V next() {
        return entryItr.next().getValue();
      }
    };
  }

  @Override
  public Spliterator<V> spliterator() {
    return CollectSpliterators.map(map.entrySet().spliterator(), Entry::getValue);
  }

  @Override

    }

    @Override
    public int encode(byte[] dst, int dstIndex) {
        int start = dstIndex;

        // Write context header
        SMBUtil.writeInt4(0, dst, dstIndex); // Next (offset to next context, 0 for last)
        dstIndex += 4;

        SMBUtil.writeInt2(16, dst, dstIndex); // NameOffset (from start of context)
        dstIndex += 2;