Modify the interface to take an IReadOnlyDictionary

[jwrosewell]

pipeline-dotnet/FiftyOne.Pipeline.Elements/FiftyOne.Pipeline.JsonBuilderElement/FlowElement/JsonBuilderElement.cs

Line 608 in 279453c

protected virtual void AddJsonValuesForProperty(

This should be made in 4.5 and is not a breaking change as it is already supported by the current type.