@Test
    public void shouldGetUsingTraverserOverload() {
        final Parameters parameters = new Parameters();
        parameters.set(null, "a", "axe", "b", "bat", "c", "cat");

        assertEquals(Collections.singletonList("axe"), parameters.get(mock(Traverser.Admin.class), "a", () -> "x"));
        assertEquals(Collections.singletonList("bat"), parameters.get(mock(Traverser.Admin.class), "b", () -> "x"));
        assertEquals(Collections.singletonList("cat"), parameters.get(mock(Traverser.Admin.class), "c", () -> "x"));
        assertEquals(Collections.singletonList("zebra"), parameters.get(mock(Traverser.Admin.class), "z", () -> "zebra"));
    }
@author Stephen Mallette (http://stephen.genoprime.com)
gremlin-core/src/test/java/org/apache/tinkerpop/gremlin/process/traversal/step/util/ParametersTest.java