public CassandraOutputFormat finish() {
            if (format.userName == null) {
                LOG.info("Username was not supplied separately.");
            }
            if (format.password == null) {
                LOG.info("Password was not supplied separately.");
            }
            if (format.address == null) {
                throw new IllegalArgumentException("No address URL supplied.");
            }
            if (format.database == null) {
                throw new IllegalArgumentException("No dababase suplied");
            }
            if (format.tableName == null) {
                throw new IllegalArgumentException("No tableName supplied");
            }
            return format;
        }
Finalizes the configuration and checks validity.

@return Configured RetractJDBCOutputFormat
cassandra/cassandra-sink/src/main/java/com/dtstack/flink/sql/sink/cassandra/CassandraOutputFormat.java