code: public void setDictionary(byte[] b, int off, int len) {
          if (b == null) {
              throw new NullPointerException();
          }
          if (off < 0 || len < 0 || off > b.length - len) {
              throw new ArrayIndexOutOfBoundsException();
          }
          synchronized (zsRef) {
              ensureOpen();
              setDictionary(zsRef.address(), b, off, len);
          }
      }
docs: Sets preset dictionary for compression. A preset dictionary is used
  when the history buffer can be predetermined. When the data is later
  uncompressed with Inflater.inflate(), Inflater.getAdler() can be called
  in order to get the Adler-32 value of the dictionary required for
  decompression.
  @param b the dictionary data bytes
  @param off the start offset of the data
  @param len the length of the data
  @see Inflater#inflate
  @see Inflater#getAdler