chore: update Checkstyle version and fix errors

[jjaakola-aiven]

No description provided.

[eliax1996]

Since its a list I would add in the test also a test regarding the retrieval of the values, something like:

Suggested change

	@Test
	public void testValidateTablesGiven() {
	final Map<String, String> properties = new HashMap<>();
	properties.put(JdbcSourceTaskConfig.TABLES_CONFIG, "test-table");
	properties.put(JdbcConfig.CONNECTION_URL_CONFIG, "connection-url");
	properties.put(JdbcSourceConnectorConfig.MODE_CONFIG, "bulk");
	properties.put(JdbcSourceConnectorConfig.TOPIC_PREFIX_CONFIG, "test-prefix");
	final JdbcSourceTaskConfig config = new JdbcSourceTaskConfig(properties);
	config.validate();
	}
	@Test
	public void testValidateTablesGiven() {
	final Map<String, String> properties = new HashMap<>();
	properties.put(JdbcSourceTaskConfig.TABLES_CONFIG, "test-table1, test-table2");
	properties.put(JdbcConfig.CONNECTION_URL_CONFIG, "connection-url");
	properties.put(JdbcSourceConnectorConfig.MODE_CONFIG, "bulk");
	properties.put(JdbcSourceConnectorConfig.TOPIC_PREFIX_CONFIG, "test-prefix");
	final JdbcSourceTaskConfig config = new JdbcSourceTaskConfig(properties);
	config.validate();
	assertEquals(config.getList(JdbcSourceTaskConfig.TABLES_CONFIG), List.of("test-table1", "test-table2"));
	}

[eliax1996]

I would like to add: encoded as a comma separated string

[eliax1996]

To me looks fine, if you wanna add the suggestion I'm happier, not mandatory. I can merge as it is if you prefer

[eliax1996]

LGTM