docs: public FilterByteBuffer get(ByteBuffer bb) throws IOException
      {
          byte[] buf = new byte[BUFSIZE];
          while (bb.hasRemaining())
          {
              int lim = Math.min(BUFSIZE, bb.remaining());
              get(buf, 0, lim);
              bb.put(buf, 0, lim);
          }
          return this;
      }