@Override
        public Set<MemoryComputeKey> getMemoryComputeKeys() {
            return new HashSet<>(Arrays.asList(
                    MemoryComputeKey.of("m1", Operator.or, true, true),
                    MemoryComputeKey.of("m2", Operator.and, true, true),
                    MemoryComputeKey.of("m3", Operator.sum, true, false)));
        }
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