@Override
    public String toString() {
        return this.getClass().getName() + " - " + handler.toString();
    }
unwrap to original/unwrapped {@link Handler}.

@see com.alibaba.ttl.TtlUnwrap#unwrap(Object)
ttl-integrations/vertx4-ttl-integration/src/main/java/com/alibaba/ttl/integration/vertx4/TtlVertxHandler.java