title: Kafka connector config error: filter.condition: Invalid json path defined
body: <p>I'm trying to use Confluent's <a href="https://docs.confluent.io/current/connect/transforms/filter.html" rel="nofollow noreferrer">Filter SMT</a> with Debezium example <a href="https://github.com/debezium/debezium-examples/tree/master/unwrap-smt" rel="nofollow noreferrer">unwrap-smt</a>.</p>
  <p>I added the following configs to source connector (Debezium MySQL) config:</p>
  <pre><code>    &quot;transforms&quot;: &quot;route,csFilter&quot;,
      ...
      ...
      &quot;transforms.csFilter.type&quot;: &quot;io.confluent.connect.transforms.Filter$Value&quot;,
      &quot;transforms.csFilter.filter.condition&quot;: &quot;$.payload.after.source == 2&quot;,
      &quot;transforms.csFilter.filter.type&quot;: &quot;exclude&quot;,
      &quot;transforms.csFilter.missing.or.null.behavior&quot;: &quot;fail&quot;
  </code></pre>
  <p>Since this Filter SMT is provided by Confluent, I downloaded the <a href="https://www.confluent.io/hub/confluentinc/connect-transforms" rel="nofollow noreferrer">jar file</a> and copied (connect-transforms, connect-utils, json-path) jar files to <code>path-to-kafka/connect/debezium-connector-mysql</code> directory.</p>
  <p>When I tried to register Debezium MySQL source connector,</p>
  <pre><code>curl -i -X POST -H &quot;Accept:application/json&quot; -H &quot;Content-Type:application/json&quot; 
  localhost:8083/connectors/ -d @source_connector_config.json
  </code></pre>
  <p>I got this error:</p>
  <pre><code>{&quot;error_code&quot;:400,
  &quot;message&quot;:&quot;Connector configuration is invalid and contains the following 1 error(s):\n
  Invalid value $.payload.after.source == 2 for configuration filter.condition: Invalid json path defined. 
  Please refer to https://github.com/json-path/JsonPath README for correct use of json path.\n
  You can also find the above list of errors at the endpoint `/{connectorType}/config/validate`&quot;}
  </code></pre>
  <p>I checked the JSON path expression with the examples provided in <a href="https://www.baeldung.com/guide-to-jayway-jsonpath" rel="nofollow noreferrer">this guide</a>. It seemed okay.</p>
  <p>Can you please point me to the right directioin? What am I missing?
  Thanks.</p>