Change translationCache implementation.

Author: VillePihlava

domain-core/src/main/java/org/opentripplanner/core/model/i18n/TranslatedString.java

@@ -71,20 +71,23 @@ public static I18NString getI18NString(
     if (translations.isEmpty()) {
       throw new IllegalArgumentException("At least one translation must be provided");
     }
-    return translationCache.computeIfAbsent(translations, k -> {
+    I18NString ret = translationCache.get(translations);
+    if (ret == null) {
       // Check if we only have one name, even under multiple languages
       boolean allValuesEqual = new HashSet<>(translations.values()).size() == 1;
       var firstLanguage = translations.keySet().iterator().next();
       boolean onlySingleUntranslatedLanguage =
         translations.size() == 1 && (firstLanguage == null || firstLanguage.isBlank());
       if (forceTranslatedString && !onlySingleUntranslatedLanguage) {
-        return new TranslatedString(translations);
+        ret = new TranslatedString(translations);
       } else if (allValuesEqual) {
-        return new NonLocalizedString(translations.values().iterator().next());
+        ret = new NonLocalizedString(translations.values().iterator().next());
       } else {
-        return new TranslatedString(translations);
+        ret = new TranslatedString(translations);
       }
-    });
+      translationCache.put(translations, ret);
+    }
+    return ret;
   }
 
   @Override