code: public CMASpace fetchOne(String spaceId) {
      assertNotNull(spaceId, "spaceId");
      return service.fetchOne(spaceId).blockingFirst();
    }
docs: Fetch a Space with a given {@code spaceId}.
  
  @param spaceId Space ID
  @return {@link CMASpace} result instance
  @throws IllegalArgumentException if space's id is null.