@Override
    public <V> Property<V> property(final String key) {
        return null != this.properties && this.properties.containsKey(key) ? this.properties.get(key).get(0) : Property.empty();
    }
@author Stephen Mallette (http://stephen.genoprime.com)
@author Marko A. Rodriguez (http://markorodriguez.com)
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/structure/util/detached/DetachedElement.java