Fixed SystemTextJson indexed properties handling.

[viktoriia-zhel]

The SystemTextJsonReflectionService did not handle properly types with indexed properties. Exception "The JSON property 'item' is defined multiple times on type" was thrown if schema had been generated for type with multiple indexed properties.

In the applied fix indexed properties are detected and not added to the generated schema.
Result schema matches schemas generated with NewtonsoftJsonReflectionService and previous versions of NJsonSchema library.

Fixes RicoSuter/NSwag#4874

[viktoriia-zhel]

@lahma Could you, please, help me with a build error that I get?

I am getting " [ERR] Compile: D:\a\NJsonSchema\NJsonSchema\src\NJsonSchema\Generation\JsonSchemaGenerator.cs(1092,25): error CA1859: Change return type of method 'TryGetInheritanceDiscriminatorConverter' from 'object?' to 'NJsonSchema.Generation.JsonSchemaGenerator.SystemTextJsonInheritanceWrapper?' for improved performance (https://learn.microsoft.com/dotnet/fundamentals/code-analysis/quality-rules/ca1859) [D:\a\NJsonSchema\NJsonSchema\src\NJsonSchema\NJsonSchema.csproj::TargetFramework=netstandard2.0]".

I tried to fix it as error message suggested, changed return type of method TryGetInheritanceDiscriminatorConverter to SystemTextJsonInheritanceWrapper. However, that broke unit test When_schema_has_base_schema_then_it_is_referenced_with_Newtonsoft.

Do you know what is a correct type to use here to fix CA1859?
Or can I disable this check for the method TryGetInheritanceDiscriminatorConverter so the build is successful?

[RicoSuter]

is this really needed?
i think this might break CI?

[viktoriia-zhel]

Yes, I think this should be reverted, it breaks test When_schema_has_base_schema_then_it_is_referenced_with_Newtonsoft.

However, without it build fails with " [ERR] Compile: D:\a\NJsonSchema\NJsonSchema\src\NJsonSchema\Generation\JsonSchemaGenerator.cs(1092,25): error CA1859: Change return type of method 'TryGetInheritanceDiscriminatorConverter' from 'object?' to 'NJsonSchema.Generation.JsonSchemaGenerator.SystemTextJsonInheritanceWrapper?' for improved performance (https://learn.microsoft.com/dotnet/fundamentals/code-analysis/quality-rules/ca1859) [D:\a\NJsonSchema\NJsonSchema\src\NJsonSchema\NJsonSchema.csproj::TargetFramework=netstandard2.0]"."

[viktoriia-zhel]

Can you suggest a better fix to CA1859?

[lahma]

You should be able to use

#pragma warning disable CA1859
private object? TryGetInheritanceDiscriminatorConverter(Type type)
#pragma warning enable CA1859