public final boolean test(final Property property) {
        if (this.key != null) {
            if (this.key.equals(T.value.getAccessor()))
                return testValue(property);
            if (this.key.equals(T.key.getAccessor()))
                return testKey(property);
        }
        if (property instanceof Element)
            return test((Element) property);
        return false;
    }
@author Marko A. Rodriguez (http://markorodriguez.com)
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/traversal/step/util/HasContainer.java