docs: public SingleOutputStreamOperator<T> returns(Class<T> typeClass) {
  		requireNonNull(typeClass, "type class must not be null.");
  
  		try {
  			return returns(TypeInformation.of(typeClass));
  		}
  		catch (InvalidTypesException e) {
  			throw new InvalidTypesException("Cannot infer the type information from the class alone." +
  					"This is most likely because the class represents a generic type. In that case," +
  					"please use the 'returns(TypeHint)' method instead.");
  		}
  	}