public ClickHouseCredentials getCredentials(ClickHouseConfig config) {
        return credentials != null ? credentials
                : ClickHouseChecker.nonNull(config, ClickHouseConfig.TYPE_NAME).getDefaultCredentials();
    }
Gets credentials for accessing this node. It first attempts to use
credentials tied to the node, and then use default credentials from the given
configuration.

@param config non-null configuration for retrieving default credentials
@return credentials for accessing this node
clickhouse-client/src/main/java/com/clickhouse/client/ClickHouseNode.java