Hopefully the test is self explanatory, but the DictionaryKeyToStringConverter ran into issues with passed Dictionary inherited classes in lists as it could not cast. More concretely, it was the SecurityRequirement class causing the issue
System.InvalidCastException : Unable to cast object of type DictionaryKeyToStringConverterInner[System.String,System.Collections.Generic.List1[System.String]] to type System.Text.Json.Serialization.JsonConverter[Saunter.AsyncApiSchema.v2.SecurityRequirement].
Hopefully the test is self explanatory, but the DictionaryKeyToStringConverter ran into issues with passed Dictionary inherited classes in lists as it could not cast. More concretely, it was the SecurityRequirement class causing the issue
System.InvalidCastException : Unable to cast object of type DictionaryKeyToStringConverterInner[System.String,System.Collections.Generic.List1[System.String]] to type System.Text.Json.Serialization.JsonConverter[Saunter.AsyncApiSchema.v2.SecurityRequirement].