builder.putAll("foo", Arrays.asList(1, 2, 3));
    builder.putAll("bar", Arrays.asList(4, 5));
    builder.putAll("foo", Arrays.asList(6, 7));
    Multimap<String, Integer> multimap = builder.build();
    assertEquals(ImmutableSet.of(1, 2, 3, 6, 7), multimap.get("foo"));
    assertEquals(ImmutableSet.of(4, 5), multimap.get("bar"));
    assertEquals(7, multimap.size());
  }

### Start Dex

```
~ ./bin/dex serve dex.yaml
time="2020-07-12T20:45:50Z" level=info msg="config issuer: http://127.0.0.1:5556/dex"
time="2020-07-12T20:45:50Z" level=info msg="config storage: sqlite3"
time="2020-07-12T20:45:50Z" level=info msg="config static client: Example App"
time="2020-07-12T20:45:50Z" level=info msg="config connector: mock"
time="2020-07-12T20:45:50Z" level=info msg="config connector: local passwords enabled"

    assertThat(graph.edges())
        .containsExactly(
            EndpointPair.unordered(1, 2),
            EndpointPair.unordered(1, 4),
            EndpointPair.unordered(1, 3),
            EndpointPair.unordered(4, 5))
        .inOrder();
  }

  @Test
  public void stableIncidentEdgeOrder_adjacentNodes_returnsInConnectingEdgeInsertionOrder() {

    builder.putAll("foo", Arrays.asList(1, 2, 3));
    builder.putAll("bar", Arrays.asList(4, 5));
    builder.putAll("foo", Arrays.asList(6, 7));
    Multimap<String, Integer> multimap = builder.build();
    assertThat(multimap.get("foo")).containsExactly(1, 2, 3, 6, 7).inOrder();
    assertThat(multimap.get("bar")).containsExactly(4, 5).inOrder();
    assertEquals(7, multimap.size());
  }

-rwxrwxrwx 1 nobody nobody           45 Apr  1 06:13 chunkdocs/metadata
226 Closing data connection, sent 75 bytes
ftp> get
(remote-file) runner/chunkdocs/metadata
(local-file) test
local: test remote: runner/chunkdocs/metadata
229 Entering Extended Passive Mode (|||37785|)
150 Data transfer starting 45 bytes
	45        3.58 KiB/s
226 Closing data connection, sent 45 bytes
45 bytes received in 00:00 (3.55 KiB/s)
...
```

    operator.read(36, buffer, 2)
    operator.read(2, buffer, 4)
    operator.write(0, buffer, buffer.size)
    operator.read(0, buffer, 12)
    operator.read(47, buffer, 3)
    operator.read(45, buffer, 2)
    operator.read(47, buffer, 3)
    operator.read(26, buffer, 10)
    operator.read(23, buffer, 3)
    operator.write(47, buffer, buffer.size)
    operator.read(62, buffer, 6)

    builder.putAll("foo", Arrays.asList(1, 2, 3));
    builder.putAll("bar", Arrays.asList(4, 5));
    builder.putAll("foo", Arrays.asList(6, 7));
    Multimap<String, Integer> multimap = builder.build();
    assertEquals(ImmutableSet.of(1, 2, 3, 6, 7), multimap.get("foo"));
    assertEquals(ImmutableSet.of(4, 5), multimap.get("bar"));
    assertEquals(7, multimap.size());
  }

    assertThat(graph.edges())
        .containsExactly(
            EndpointPair.unordered(1, 2),
            EndpointPair.unordered(1, 4),
            EndpointPair.unordered(1, 3),
            EndpointPair.unordered(4, 5))
        .inOrder();
  }

  @Test
  public void stableIncidentEdgeOrder_adjacentNodes_returnsInConnectingEdgeInsertionOrder() {

            validator.safeAdd(Integer.MIN_VALUE, -1);
        });
    }

    @Test
    public void testSafeMultiply() throws Exception {
        assertEquals(20, validator.safeMultiply(4, 5));
        assertEquals(-20, validator.safeMultiply(-4, 5));
        assertEquals(0, validator.safeMultiply(0, 1000));
    }

    @Test
    public void testSafeMultiplyOverflow() throws Exception {

        @Override
        protected ListIterator<Entry<String, Integer>> newTargetIterator() {
          multimap = create();
          multimap.putAll("foo", asList(2, 3));
          multimap.putAll("bar", asList(4, 5));
          multimap.put("foo", 6);
          return multimap.entries().listIterator(startIndex);
        }

        @Override
        protected void verify(List<Entry<String, Integer>> elements) {