code: public CMALocale fetchOne(String spaceId, String environmentId, String localeId) {
      assertNotNull(spaceId, "spaceId");
      assertNotNull(environmentId, "environmentId");
      assertNotNull(localeId, "localeId");
  
      return service.fetchOne(spaceId, environmentId, localeId).blockingFirst();
    }
docs: Fetches one locale by its id from the given space and environment.
  <p>
  This method will override the configuration specified through
  {@link CMAClient.Builder#setSpaceId(String)} and
  {@link CMAClient.Builder#setEnvironmentId(String)}.
  
  @param spaceId       the space this environment is hosted in.
  @param environmentId the environment this locale is hosted in.
  @param localeId      the id of the locale to be found.
  @return null if no locale was found, otherwise the found locale.
  @throws IllegalArgumentException if space id is null.
  @throws IllegalArgumentException if environment id is null.
  @throws IllegalArgumentException if locale id is null.