public void AddImports(ProjectId projectId, ImmutableArray <string> imports)
{
if (projectId == null)
{
throw new ArgumentNullException(nameof(projectId));
}
var project = CurrentSolution.GetProject(projectId);
var compilationOptions = (CSharpCompilationOptions)project.CompilationOptions;
SetCurrentSolution(
CurrentSolution.WithProjectCompilationOptions(
projectId,
compilationOptions.WithUsings(imports)));
}