/// <summary>
        /// Creates a composed model from a collection of existing trained models with labels.
        /// </summary>
        /// <param name="modelIds">List of model ids to use in the composed model.</param>
        /// <param name="createComposedModelOptions">A set of options available for configuring the create composed model request.</param>
        /// <param name="cancellationToken">A <see cref="CancellationToken"/> controlling the request lifetime.</param>
        /// <returns>
        /// <para>A <see cref="CreateComposedModelOperation"/> to wait on this long-running operation. Its Value upon successful
        /// completion will contain meta-data about the composed model.</para>
        /// </returns>
        public virtual CreateComposedModelOperation StartCreateComposedModel(IEnumerable <string> modelIds, CreateComposedModelOptions createComposedModelOptions = default, CancellationToken cancellationToken = default)
        {
            Argument.AssertNotNull(modelIds, nameof(modelIds));
            createComposedModelOptions ??= new CreateComposedModelOptions();

            using DiagnosticScope scope = Diagnostics.CreateScope($"{nameof(FormTrainingClient)}.{nameof(StartCreateComposedModel)}");
            scope.Start();

            try
            {
                var modelIdsGuid = new List <Guid>();
                foreach (var modelId in modelIds)
                {
                    modelIdsGuid.Add(ClientCommon.ValidateModelId(modelId, nameof(modelId)));
                }

                var composeRequest = new ComposeRequest(modelIdsGuid);
                if (createComposedModelOptions.ModelName.Length > 0)
                {
                    composeRequest.ModelName = createComposedModelOptions.ModelName;
                }

                ResponseWithHeaders <FormRecognizerComposeCustomModelsAsyncHeaders> response = ServiceClient.ComposeCustomModelsAsync(composeRequest);
                return(new CreateComposedModelOperation(response.Headers.Location, ServiceClient, Diagnostics));
            }
            catch (Exception e)
            {
                scope.Failed(e);
                throw;
            }
        }