code: private void writeEXT(ZipEntry e) throws IOException {
          writeInt(EXTSIG);           // EXT header signature
          writeInt(e.crc);            // crc-32
          if (e.csize >= ZIP64_MAGICVAL || e.size >= ZIP64_MAGICVAL) {
              writeLong(e.csize);
              writeLong(e.size);
          } else {
              writeInt(e.csize);          // compressed size
              writeInt(e.size);           // uncompressed size
          }
      }
docs: /*
  Writes extra data descriptor (EXT) for specified entry.