code: public static TrainingApi authenticate(String baseUrl, ServiceClientCredentials credentials, final String apiKey) {
          return new TrainingApiImpl(baseUrl, credentials).withApiKey(apiKey);
      }
docs: Initializes an instance of Custom Vision Training API client.
  
  @param baseUrl the base URL of the service
  @param credentials the management credentials for Azure
  @param apiKey the Custom Vision Training API key
  @return the Custom Vision Training API client