question: public static byte [ ] checkIndexHeaderID ( DataInput in , byte [ ] expectedID ) throws IOException { byte id [ ] = new byte [ StringHelper . ID_LENGTH ] ; in . readBytes ( id , 0 , id . length ) ; if ( ! Arrays . equals ( id , expectedID ) ) { throw new CorruptIndexException ( "file mismatch, expected id=" + StringHelper . idToString ( expectedID ) + ", got=" + StringHelper . idToString ( id ) , in ) ; } return id ; }
target:  Expert: just reads and verifies the object ID of an index header 