docs: public static String toOpcodeName(int opcode)
      {
          switch (opcode)
          {
              case CONTINUATION:
                  return "CONTINUATION";
  
              case TEXT:
                  return "TEXT";
  
              case BINARY:
                  return "BINARY";
  
              case CLOSE:
                  return "CLOSE";
  
              case PING:
                  return "PING";
  
              case PONG:
                  return "PONG";
  
              default:
                  break;
          }
  
          if (0x1 <= opcode && opcode <= 0x7)
          {
              return String.format("DATA(0x%X)", opcode);
          }
  
          if (0x8 <= opcode && opcode <= 0xF)
          {
              return String.format("CONTROL(0x%X)", opcode);
          }
  
          return String.format("0x%X", opcode);
      }