Data model used for the examples below

JavaStreamModal.java

@Getter @Setter @Builder @ToString(of = {"name", "city"})
public class Consumer {
    private String name;
    private String city;
    private int age;
    private List<Thing> things;
}

@Setter @Getter @Builder @ToString(of = {"name"})
public class Thing {// Device in IoT
    private String id;
    private String name;
    private boolean isRunning;
    private Type type;
    private List<Event> events;
    private int cost;
}

@Getter @Setter @Builder @ToString(of = {"name"})
public class Event {
    private String name;
    private boolean isActive;
}

public enum Type {
    HOME, FIELD, COMMUNICATION, HEALTH
}