Say I have following java POJOs

class Outer {
  Config;
  List<Warning> warnings;

}

class Config {
  String configId;
  String configName;
}

class Warning {
  String warningId;
  String warningName;
}


class Transformed {
  String configId
  String configName;
  String warningId;
  String warningName;
}

Desired output
List<Transformed>

In an ideal world where for ever instance of Outer, if warnings were always present I could use Java 8 streams and transform into List<Transformed. But List<Warning> warnings can be null in some cases of input. One might say, use something like Stream.ofNullable when doing an inner stream. This will not work in my use case because I still want the Tranformed instance to have the fields String configId and String configName populated even if the warning fields are null. How do I do it with Java 8 streams, and filter combo? What is the ideal way? Or I just go the plain old fashioned nested looping way with null checks and all?