code: public CMAArray<CMAApiKey> fetchAll(String spaceId) {
      assertNotNull(spaceId, "spaceId");
      return service.fetchAll(spaceId).blockingFirst();
    }
docs: Fetch all delivery api keys from the given space.
  <p>
  This method will override the configuration specified through
  {@link CMAClient.Builder#setSpaceId(String)} and will ignore
  {@link CMAClient.Builder#setEnvironmentId(String)}.
  
  @param spaceId the id of the space to host the api keys.
  @return a list of delivery api keys.
  @throws IllegalArgumentException if spaceId is null.