code: public CMAEnvironment fetchOne(String spaceId, String environmentId) {
      assertNotNull(spaceId, "spaceId");
      assertNotNull(environmentId, "environmentId");
      return service.fetchOne(spaceId, environmentId).blockingFirst();
    }
docs: Fetch an environment with a given {@code environmentId} and space.
  <p>
  This method will override the configuration specified through
  {@link CMAClient.Builder#setSpaceId(String)}.
  
  @param spaceId       space ID
  @param environmentId environment ID
  @return {@link CMAEnvironment} result instance
  @throws IllegalArgumentException if space id is null.
  @throws IllegalArgumentException if environment's id is null.