presto-hive/src/main/java/io/prestosql/plugin/hive/s3select/S3SelectLineRecordReader.java/S3SelectLineRecordReader/getFieldDelimiter
class S3SelectLineRecordReader:    String getFieldDelimiter(Properties schema)
    {
        return schema.getProperty(FIELD_DELIM, schema.getProperty(SERIALIZATION_FORMAT));
    }