code: public String getDefaultParentForEntityInRealm(String entType, String realmName) throws WIMException {
          String defaultParent = getDefaultParent(entType);
          if (realmName != null) {
              validateRealmName(realmName);
              String parent = null;
              RealmConfig realmConfig = getRealmConfig(realmName);
              Map defaultParentsMap = realmConfig.getDefaultParentMapping();
              if (defaultParentsMap != null) {
                  parent = (String) defaultParentsMap.get(entType);
                  if (parent != null) {
                      defaultParent = parent;
                  }
              }
              if (parent == null && !isUniqueNameInRealm(defaultParent, realmName)) {
                  defaultParent = null;
              }
          }
          return defaultParent;
      }
docs: Gets the default parent node that is for the specified entity type in specified realm.
  
  @param entType The entity type. e.g. Person, Group...
  @param realmName The name of the realm
  @return The default parent node.