public String offsetsTopic() {
        return null;
    }
Get the internal topic used by this worker to store source connector offsets.
The default implementation returns {@code null} and should be overridden by subclasses
if the worker mode for the subclass uses an internal offsets topic.
@return the name of the internal offsets topic, or {@code null} if the worker does not use
an internal offsets topic
connect/runtime/src/main/java/org/apache/kafka/connect/runtime/WorkerConfig.java