IDictionary doesn't work with Fsharp dictionary implementation

[Lanayx]

🐛 Bug Report

Affected Languages

• TypeScript or Javascript
• Python
• Java
• .NET (F#)

General Information

• JSII Version: 0.22.0
• Platform: Windows 10

What is the problem?

Properties whose type is IDictionary (for example Environment property in different templates) can't take F# dictionary like
Environment = dict [("alertEmails", alertEmails)]
to make it work I have to convert it into Dictionary like
Environment = Dictionary(dict [("alertEmails", alertEmails)])
which is undesirable.

The problem is that on this line valueType.GetProperty("Keys") returns null, while if I check ((IDictionary<string, string>) value).Keys it works.

Verbose Log

Unhandled exception. System.NullReferenceException: Object reference not set to an instance of an object.
   at Amazon.JSII.Runtime.Services.Converters.FrameworkToJsiiConverter.TryConvertMap(IReferenceMap referenceMap, TypeReference elementType, Object value, Object& result)
   at Amazon.JSII.Runtime.Services.Converters.ValueConverter.TryConvertCollection(IReferenceMap referenceMap, Object value, Boolean isOptional, CollectionTypeReference collectionType, Object& result)
   at Amazon.JSII.Runtime.Services.Converters.ValueConverter.TryConvert(IOptionalValue optionalValue, Type type, IReferenceMap referenceMap, Object value, Object& result)
   at Amazon.JSII.Runtime.Services.Converters.FrameworkToJsiiConverter.TryConvertClass(Type type, IReferenceMap referenceMap, Object value, Object& result)
   at Amazon.JSII.Runtime.Services.Converters.ValueConverter.TryConvertCustomType(Type type, IReferenceMap referenceMap, Object value, Boolean isOptional, String fullyQualifiedName, Object& result)
   at Amazon.JSII.Runtime.Services.Converters.ValueConverter.TryConvert(IOptionalValue optionalValue, Type type, IReferenceMap referenceMap, Object value, Object& result)
   at Amazon.JSII.Runtime.Services.Converters.FrameworkToJsiiConverter.TryConvert(IOptionalValue optionalValue, IReferenceMap referenceMap, Object value, Object& result)
   at Amazon.JSII.Runtime.Deputy.DeputyBase.<>c__DisplayClass20_0.<ConvertArguments>b__0(Parameter parameter, Object frameworkArgument)
   at System.Linq.Enumerable.ZipIterator[TFirst,TSecond,TResult](IEnumerable`1 first, IEnumerable`1 second, Func`3 resultSelector)+MoveNext()

[Lanayx]

This is an example of the fix for the similar issue in another library
https://github.com/Cysharp/MagicOnion/pull/207/files

[MrArnoldPalmer]

@Lanayx thanks for pointing out a possible fix. This seems relatively simple to implement.

[Lanayx]

@MrArnoldPalmer even easier fix will be to cast value to IDictionary instead of using reflection since you are trying to access properties of this interface anyway