@Override
        public void execute(final Vertex vertex, final Messenger messenger, final Memory memory) {
            if (memory.isInitialIteration()) {
                assertFalse(vertex.property("v1").isPresent());
                assertFalse(vertex.property("v2").isPresent());
                assertFalse(vertex.property("v3").isPresent());
                vertex.property("v1", "shouldNotExist");
                vertex.property("v2", "shouldNotExist");
                vertex.property("v3", "shouldExist");
                assertTrue(vertex.property("v1").isPresent());
                assertTrue(vertex.property("v2").isPresent());
                assertTrue(vertex.property("v3").isPresent());
                assertEquals("shouldNotExist", vertex.value("v1"));
                assertEquals("shouldNotExist", vertex.value("v2"));
                assertEquals("shouldExist", vertex.value("v3"));
                //
                assertFalse(memory.exists("m1"));
                assertFalse(memory.exists("m2"));
                assertFalse(memory.exists("m3"));
                memory.add("m1", false);
                memory.add("m2", true);
                memory.add("m3", 2l);
                // should still not exist as this pulls from the master memory
                assertFalse(memory.exists("m1"));
                assertFalse(memory.exists("m2"));
                assertFalse(memory.exists("m3"));

            } else {
                assertTrue(vertex.property("v1").isPresent());
                assertTrue(vertex.property("v2").isPresent());
                assertTrue(vertex.property("v3").isPresent());
                assertEquals("shouldNotExist", vertex.value("v1"));
                assertEquals("shouldNotExist", vertex.value("v2"));
                assertEquals("shouldExist", vertex.value("v3"));
                //
                assertTrue(memory.exists("m1"));
                assertTrue(memory.exists("m2"));
                assertTrue(memory.exists("m3"));
                assertFalse(memory.get("m1"));
                assertTrue(memory.get("m2"));
                assertEquals(12l, memory.<Long>get("m3").longValue());
                memory.add("m1", true);
                memory.add("m2", true);
                memory.add("m3", 2l);
            }
        }
Javadoc for {@code ConcurrentSkipListSet} includes this little note: "Beware that, unlike in most
collections, the size method is not a constant-time operation." Doing a traversal of elements will yield
the correct count. Java 11 upgrade seemed to force this failure consistently.
gremlin-test/src/main/java/org/apache/tinkerpop/gremlin/process/computer/GraphComputerTest.java