code: public CMAEntry fetchOne(String spaceId, String environmentId, String entryId) {
      assertNotNull(spaceId, "spaceId");
      assertNotNull(environmentId, "environmentId");
      assertNotNull(entryId, "entryId");
      return service.fetchOne(spaceId, environmentId, entryId).blockingFirst();
    }
docs: Fetch an entry with the given entryId from the given environment and space.
  
  @param spaceId       Space ID
  @param environmentId Environment ID
  @param entryId       Entry ID
  @return {@link CMAEntry} result instance
  @throws IllegalArgumentException if space id is null.
  @throws IllegalArgumentException if environment id is null.
  @throws IllegalArgumentException if entry id is null.