code: @Override
      public StringConverter<?> findConverter(Class<?> cls) {
          if (cls == Byte[].class) {
              return ByteArrayStringConverter.INSTANCE;
          }
          return null;
      }
docs: Finds a converter by type.
  
  @param cls  the type to lookup, not null
  @return the converter, null if not found
  @throws RuntimeException (or subclass) if source code is invalid