The <K> class in a groupByKey(…) has a Map among its members. The groupByKey operation fails on an “un-comparable” problem
问题 I have a class Entreprise that have primives data types and a Map on another class : Etablissement that is only made of primitive data types. public class Entreprise implements Comparable<Entreprise> { /** Liste des établissements de l'entreprise. */ private Map<String, Etablissement> etablissements = new HashMap<>(); /** Sigle de l'entreprise */ private String sigle; /** Nom de naissance */ private String nomNaissance; /** Nom d'usage */ private String nomUsage; ... @Override public int