title: Flutter : mqtt topic can only be english?
body: <p>For my Flutter project, I am using <code>mqtt_client: ^9.7.2</code>.</p>
  <p>I want to subscribe &amp; publish to a Korean topic and send/receive Korean payloads.</p>
  <p>When I subscribe and publish to an English topic, like &quot;test/hi&quot;, the payload decodes well using utf8.</p>
  <p>However, if I try to subscribe to Korean topics, then it doesn't work.</p>
  <p>If I try subscribing to &quot;test/안녕&quot;, then nothing happens.</p>
  <p>What I want :</p>
  <pre><code>EXAMPLE::Subscribing to the test/안녕 topic
  EXAMPLE::Subscription confirmed for topic test/안녕
  EXAMPLE::Publishing our topic
  EXAMPLE::Published notification:: topic is test/안녕, with Qos MqttQos.exactlyOnce
  EXAMPLE::Change notification:: topic is &lt;test/안녕&gt;, payload is &lt;-- Hello 안녕하세요 --&gt;
  </code></pre>
  <p>What is happening :</p>
  <pre><code>EXAMPLE::Subscribing to the test/안녕 topic
  EXAMPLE::Publishing our topic
  </code></pre>