Rejecting a record through topic's Schema

My goal is I want to use Java to produce a record to a topic.
If the record does not match the existing schema on topic, the record should be rejected.

I had follow the steps on the below page and able to produce a record to a topic.
However, there appears to be no schema validation from the topic side.
If I send records not matching the schema that is on the topic, the records still go through.

Is there additional configuration necessary?

Did you set

Keep in mind that topics do not have schemas. Server-side validation is only available in Confluent Server.

The JSONSchemaSerializer on the client-side is what will accept/deny any events from continuing to the topic.