docs: public <K> DistinctOperator<T> distinct(KeySelector<T, K> keyExtractor) {
  		TypeInformation<K> keyType = TypeExtractor.getKeySelectorTypes(keyExtractor, getType());
  		return new DistinctOperator<>(this, new Keys.SelectorFunctionKeys<>(keyExtractor, getType(), keyType), Utils.getCallLocationName());
  	}