in EnvDTE.Host/Callback/Util/SolutionExtensions.cs [82:93]
public static void SetActiveConfigurationAndPlatform([NotNull] this ISolution solution,
[NotNull] SolutionConfigurationAndPlatform configuration)
{
var solutionMark = solution.GetSolutionMark();
if (solutionMark is null) return;
if (!solutionMark.ConfigurationAndPlatformStore.ConfigurationsAndPlatforms.Contains(configuration))
throw new ArgumentException(InvalidSolutionConfigurationMessage);
var activeConfigurationManager = solution.GetComponent<IActiveConfigurationManager>();
activeConfigurationManager.ActiveConfigurationAndPlatform.SetValue(configuration);
}