code: public CMASnapshot fetchOneSnapshot(CMAContentType contentType, String snapshotId) {
      assertNotNull(contentType, "contentType");
      assertNotNull(snapshotId, "snapshotId");
  
      final String contentTypeId = getResourceIdOrThrow(contentType, "contentType");
      final String spaceId = getSpaceIdOrThrow(contentType, "contentType");
      final String environmentId = contentType.getEnvironmentId();
  
      return service.fetchOneSnapshot(
          spaceId,
          environmentId,
          contentTypeId,
          snapshotId
      ).blockingFirst();
    }
docs: Fetch a specific snapshot of this content type.
  
  @param contentType the contentType whose snapshot to be returned.
  @param snapshotId  the snapshot to be returned.
  @return an array of snapshots.
  @throws IllegalArgumentException if contentType is null.
  @throws IllegalArgumentException if contentType's id is null.
  @throws IllegalArgumentException if contentType's space id is null.
  @throws IllegalArgumentException if snapshotId is null.