code: static void encodeLiteral(ByteBuf in, ByteBuf out, int length) {
          if (length < 61) {
              out.writeByte(length - 1 << 2);
          } else {
              int bitLength = bitsToEncode(length - 1);
              int bytesToEncode = 1 + bitLength / 8;
              out.writeByte(59 + bytesToEncode << 2);
              for (int i = 0; i < bytesToEncode; i++) {
                  out.writeByte(length - 1 >> i * 8 & 0x0ff);
              }
          }
  
          out.writeBytes(in, length);
      }
docs: Writes a literal to the supplied output buffer by directly copying from
  the input buffer.  The literal is taken from the current readerIndex
  up to the supplied length.
  
  @param in The input buffer to copy from
  @param out The output buffer to copy to
  @param length The length of the literal to copy