docs: private static List<Integer> exploreExtensions(ByteBuffer input, List<Integer> ciphers)
              throws SSLException {
          int length = getInt16(input);           // length of extensions
          while (length > 0) {
              int extType = getInt16(input);      // extenson type
              int extLen = getInt16(input);       // length of extension data
              if (extType == 16) {      // 0x00: ty
                  return ciphers;
              } else {                    // ignore other extensions
                  processByteVector(input, extLen);
              }
  
              length -= extLen + 4;
          }
          return null;
      }