code: public VerifyResult verifyFaceToFace(UUID faceId1, UUID faceId2) {
          return verifyFaceToFaceWithServiceResponseAsync(faceId1, faceId2).toBlocking().single().body();
      }
docs: Verify whether two faces belong to a same person or whether one face belongs to a person.
  
  @param faceId1 FaceId of the first face, comes from Face - Detect
  @param faceId2 FaceId of the second face, comes from Face - Detect
  @throws IllegalArgumentException thrown if parameters fail the validation
  @throws APIErrorException thrown if the request is rejected by server
  @throws RuntimeException all other wrapped checked exceptions if the request fails to be sent
  @return the VerifyResult object if successful.