question: public Reader freeze ( boolean trim ) { if ( frozen ) { throw new IllegalStateException ( "already frozen" ) ; } if ( didSkipBytes ) { throw new IllegalStateException ( "cannot freeze when copy(BytesRef, BytesRef) was used" ) ; } if ( trim && upto < blockSize ) { final byte [ ] newBlock = new byte [ upto ] ; System . arraycopy ( currentBlock , 0 , newBlock , 0 , upto ) ; currentBlock = newBlock ; } if ( currentBlock == null ) { currentBlock = EMPTY_BYTES ; } addBlock ( currentBlock ) ; frozen = true ; currentBlock = null ; return new PagedBytes . Reader ( this ) ; }
target:  Commits final byte[], trimming it if necessary and if trim=true 