public FileSystemFileProvider(BuiltinLibraries builtins = null)
 {
     if (builtins == null)
     {
         builtins = BuiltinLibraries.Default();
     }
     this.builtins = builtins;
 }
 public InMemoryFileProvider(BuiltinLibraries builtins = null)
 {
     if (builtins == null)
     {
         builtins = BuiltinLibraries.Default();
     }
     this.builtins = builtins;
 }