question: private void applyHeaderMask ( ByteBuffer buffer ) { byte [ ] headerMask = _format . HEADER_MASK ; for ( int idx = 0 ; idx < headerMask . length ; ++ idx ) { int pos = idx + _format . OFFSET_MASKED_HEADER ; byte b = ( byte ) ( buffer . get ( pos ) ^ headerMask [ idx ] ) ; buffer . put ( pos , b ) ; } }
target:  Applies the XOR mask to the database header in the given buffer.