code: public CMALocale update(CMALocale locale) {
      assertNotNull(locale, "locale");
  
      final String id = getResourceIdOrThrow(locale, "locale");
      final String spaceId = getSpaceIdOrThrow(locale, "locale");
      final String environmentId = locale.getEnvironmentId();
      final Integer version = getVersionOrThrow(locale, "update");
  
      final CMASystem sys = locale.getSystem();
      locale.setSystem(null);
  
      try {
        return service.update(spaceId, environmentId, id, locale, version).blockingFirst();
      } finally {
        locale.setSystem(sys);
      }
    }
docs: Update the given locale instance on Contentful.
  <p>
  Please make sure that the instance provided is fetched from Contentful. Otherwise you will
  get an exception thrown.
  
  @param locale the locale fetched from Contentful, updated by caller, to be updated.
  @return the updated locale.
  @throws IllegalArgumentException if space id is null.
  @throws IllegalArgumentException if locale is null.
  @throws IllegalArgumentException if locale id is null.
  @throws IllegalArgumentException if locale does not have a version attached.