anchor.diff:  
   // tests with maps and parenthesis
   var l6 = new A({1: // LINT
  -                   // ^^^^ Should be OK (https://github.com/dart-lang/linter/issues/885)
     []});// LINT
   var l7 = new A(const {1: const []});// OK
   var l8 = new A((([])));// LINT
  
positive.code: 
  // tests for nested maps
  var m3 = new A({ // LINT
                   // ^^^^ Should be OK (https://github.com/dart-lang/linter/issues/885)
    1: {}}); // LINT
  var m4 = new A({ // LINT
    1: const{}}); // OK
  
negative.code: 
  // tests with lists and parenthesis
  var m6 = new A([ // LINT
    {}]);// LINT
  var m7 = new A(const [const {}]);// OK
  var m8 = new A((({})));// LINT
  