title: How to specify regex for route on content processor in NiFi?
body: <p>In nifi, I am routing based on content. I am using nifi's RouteOnContent So, how can I route by specifying the regex</p>
  
  <p>My input content is:</p>
  
  <pre><code>{
  "testreg":{
  "test1":"test2",
  "test3":"test4"
  }
  }
  </code></pre>
  
  <p>I wanted to test whether <code>testreg</code> whole content(word) present in the flowfile content.
  So, I checked with </p>
  
  <ol>
  <li><code>testreg</code></li>
  <li><code>(testreg)</code></li>
  <li><code>.*testreg.*</code></li>
  <li><code>(.*testreg.*)</code></li>
  </ol>
  
  <p>But it is not matching with content, So, what is the correct regex to be used in Nifi. </p>