code: public Observable<ServiceResponse<VerifyResult>> verifyFaceToFaceWithServiceResponseAsync(UUID faceId1, UUID faceId2) {
          if (this.client.azureRegion() == null) {
              throw new IllegalArgumentException("Parameter this.client.azureRegion() is required and cannot be null.");
          }
          if (faceId1 == null) {
              throw new IllegalArgumentException("Parameter faceId1 is required and cannot be null.");
          }
          if (faceId2 == null) {
              throw new IllegalArgumentException("Parameter faceId2 is required and cannot be null.");
          }
          VerifyFaceToFaceRequest bodyParameter = new VerifyFaceToFaceRequest();
          bodyParameter.withFaceId1(faceId1);
          bodyParameter.withFaceId2(faceId2);
          String parameterizedHost = Joiner.on(", ").join("{AzureRegion}", this.client.azureRegion());
          return service.verifyFaceToFace(this.client.acceptLanguage(), bodyParameter, parameterizedHost, this.client.userAgent())
              .flatMap(new Func1<Response<ResponseBody>, Observable<ServiceResponse<VerifyResult>>>() {
                  @Override
                  public Observable<ServiceResponse<VerifyResult>> call(Response<ResponseBody> response) {
                      try {
                          ServiceResponse<VerifyResult> clientResponse = verifyFaceToFaceDelegate(response);
                          return Observable.just(clientResponse);
                      } catch (Throwable t) {
                          return Observable.error(t);
                      }
                  }
              });
      }
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
  @return the observable to the VerifyResult object