anchor.diff:          DartType iterableType = _typeProvider.iterableType(elementType);
           context = CollectionLiteralContext(
               elementType: elementType, iterableType: iterableType);
  -        if (!_uiAsCodeEnabled &&
  -            elements.isEmpty &&
  -            node.typeArguments == null &&
  -            node.isMap) {
  -          // The node is really an empty set literal with no type arguments.
  -          node.becomeMap();
  -        }
         } else if (typeArguments.length == 2) {
           DartType keyType = typeArguments[0];
           DartType valueType = typeArguments[1];
  
positive.code:       this._typeProvider,
        this._errorReporter,
        this._strictInference,
        this._uiAsCodeEnabled,
        this._isNonNullableByDefault,
        this._migratableAstInfoProvider);
  
  
negative.code:       assert(literalResolution.kind == _LiteralResolutionKind.ambiguous);
        literalType = null;
      }
      CollectionLiteralContext? context;
      if (literalType is InterfaceType) {
        List<DartType> typeArguments = literalType.typeArguments;
  