Hive Streaming API jars are sometimes shaded with a different prefix when used in environments where another version of hive already exists (spark for example). In most cases, shading is done with rename of classes with some prefix. If an uber/assembly jar is generated with renamed prefix, Hive Streaming API will not work as Hive Streaming API will reflectively instantiate outputformat class using FQCN string provided by metastore table storage descriptor object.
RecordWriter will create instance of OutputFormat using string "org.apache.hadoop.hive.ql.io.orc.OrcOutputFormat". When a shaded jar with renamed class references are used, this class will not be found by the classloader.
We can optionally accept a shade prefix from user via config which will be tried (as fallback) when ClassNotFoundException is thrown.