KSQL describe connector "connect-name"; not returning topics or sources

[credmond]

Describe the bug
describe connector "connect-name"; not returning topics or sources even though there are topics and sources. This is using an external Kafka Connect (whose APIs do return topic and source info).

To Reproduce
Run KSQL: describe connector "connector-name";

Expected behavior
For topics and sources to be populated with the correct data, not empty.

Actual behaviour

[
	{
		"@type": "connector_description",
		"statementText": "describe connector \"connector-name\";",
		"connectorClass": "io.confluent.connect.github.GithubSourceConnector",
		"status": {
			"name": "connect0-github-source",
			"connector": {
				"state": "RUNNING",
				"worker_id": "kafka-connect0:8083"
			},
			"tasks": [
				{
					"id": 0,
					"state": "RUNNING",
					"worker_id": "kafka-connect0:8083"
				}
			],
			"type": "source"
		},
		"sources": [],
		"topics": [],
		"warnings": []
	}
]