[CSHARP] Default headers overwritten instead of duplicated | Body par…

[maciejcymanski132]

@mandrean @shibayan @Blackclaws

Hello,

I fixed two issues I ran into recently.

First, when both the default configuration and the request options added the same header (like Authorization), the header was duplicated. Now, the request options override the default headers so that the header only appears once.

Second, there was a problem with how POST request bodies were being serialized. They were missing quotes and other formatting details, causing errors on the server. I’ve updated the serialization process to ensure the body is formatted correctly.

Please let me know if you need any changes.

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[BryanAldrich]

Just FYI, running on a windows environment causes the \ and / differences as well as line ending changes which the build bot notices. I had to run my builds in a WSL environment which made the changes much cleaner.