[BUG] NullPointer exception in DefaultKafkaClusterConfigSupplier get API

[kkondaka]

Describe the bug
NullPointer exception in DefaultKafkaClusterConfigSupplier get API

To Reproduce
Start pipeline with the following YAML file, it crashes because the kafkaClusterConfig is null

kafka-pipeline:
  source:
    kafka:
      bootstrap_servers: ["localhost:9092"]
      acknowledgments: true
      encryption:
        type: none
      topics:
         - name: "TestTopic"
           group_id: "TestGroup"
  sink:
    - stdout:

Expected behavior
The pipeline should start successfully.

Screenshots
If applicable, add screenshots to help explain your problem.

Environment (please complete the following information):

• OS: [e.g. Ubuntu 20.04 LTS]
• Version [e.g. 22]

Additional context
Add any other context about the problem here.