@Test
    public void shouldReturnNoCustomizers() {
        final GremlinScriptEngineManager mgr = new DefaultGremlinScriptEngineManager();
        mgr.addPlugin(ImportGremlinPlugin.build()
                .classImports(java.awt.Color.class)
                .appliesTo(Collections.singletonList("fake-script-engine")).create());
        assertEquals(0, mgr.getCustomizers(ENGINE_TO_TEST).size());
    }
This is an important test case in that it validates that core features of {@code ScriptEngine} instances that claim
to be "Gremlin-enabled" work in the expected fashion.

@author Stephen Mallette (http://stephen.genoprime.com)
gremlin-test/src/main/java/org/apache/tinkerpop/gremlin/jsr223/GremlinEnabledScriptEngineTest.java