private IEnumerable <DependencyModel> GetDependecies(PackageRetrieveOptions options)
        {
            //todo:fix dependencyset issue.
            var nuspecDependencies = _manifest.Metadata
                                     .DependencySets.First()
                                     .Dependencies.Select(d => new DependencyModel
            {
                Id      = d.Id,
                Version = d.Version
            }).ToList();

            var projetDependencies = _nugetPackageManager.GetProjectDependencies(options)
                                     .Select(d => new DependencyModel
            {
                Id      = d.Id,
                Version = d.Version
            }).ToList();


            var finalDependencies = new List <DependencyModel>();

            finalDependencies.AddRange(projetDependencies);

            foreach (var nuspecDependency in nuspecDependencies)
            {
                if (!finalDependencies.Contains(nuspecDependency, new DependencyModelIdComparator()))
                {
                    finalDependencies.Add(nuspecDependency);
                }
            }

            return(finalDependencies);
        }