Fix/csharp reserved headers and file parameter not serialising correctly by BottlecapDave · Pull Request #23593 · OpenAPITools/openapi-generator

BottlecapDave · 2026-04-21T08:09:45Z

This PR fixes a couple of issues

Fixes issue with certain reserved headers being added to the request object instead of the content object (fixes Misused header name 'Content-Range' when generating .NET API client #21727)
Fixes issue with serialising of FileParameter parameters which are incorrectly JSON serialised as the content instead of the contained stream
Updates samples based on template changes

I've tested this locally via template overrides. I'm not sure what else needs to be included for this PR.

@mandrean, @shibayan, @Blackclaws, @lucamazzanti, @iBicha

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Summary by cubic

Fixes request building in the C# generichost client so reserved headers and file uploads are handled correctly. Fixes #21727.

Bug Fixes
- Route reserved content headers (e.g., content-type, content-length, content-language, content-disposition) to HttpContent headers instead of the request message.
- Serialize FileParameter as the contained stream (not JSON) for correct file upload behavior.
Refactors
- Centralized content header detection in ClientUtils (IsContentHeader) with a header list compatible with older .NET versions; updated templates to use it.
- Regenerated C# generichost samples to reflect template changes.

^{Written for commit dd199ab. Summary will update on new commits.}

…tead of the content

…alised

cubic-dev-ai

No issues found across 158 files

Note: This PR contains a large number of files. cubic only reviews up to 75 files per PR, so some files may not have been reviewed. cubic prioritises the most important files to review.

wing328 · 2026-04-21T08:40:40Z

thanks for the PR

cc @devhl-labs

devhl-labs · 2026-04-22T01:22:14Z

        private JsonSerializerOptions _jsonSerializerOptions;

+        private readonly string[] _contentHeaders =
+        [


Consider making this static readonly, or move it to ClientUtils.

Moved to ClientUtils

devhl-labs · 2026-04-22T01:22:54Z

+            "content-type",             
+            "expires",                  
+            "last-modified",            
+            "extension-header"


Copilot is telling me extension-header is demonstrating the format, but isn't a real entry. Consider removing it. I'd also appreciate if you remove the spaces that appear after these values.

devhl-labs · 2026-04-22T01:24:26Z

-                    httpRequestMessageLocalVar.Content = ({{paramName}}{{^required}}.Value{{/required}} as object) is System.IO.Stream stream
-                        ? httpRequestMessageLocalVar.Content = new StreamContent(stream)
-                        : httpRequestMessageLocalVar.Content = new StringContent(JsonSerializer.Serialize({{paramName}}{{^required}}.Value{{/required}}, _jsonSerializerOptions));
+                    if (({{paramName}}{{^required}}.Value{{/required}} as object) is System.IO.Stream stream)


In generichost I don't believe it will ever be a System.IO.Stream anymore, I think its always going to be a FileParameter. Im not positive though. Worth looking into. You can leave this alone if you want though.

edit - I had copilot check and despite the type mapping being a Stream, the templates actually use FileParameter, so it should be safe to remove.

cubic-dev-ai

17 issues found across 207 files (changes from recent commits).

Note: This PR contains a large number of files. cubic only reviews up to 75 files per PR, so some files may not have been reviewed. cubic prioritises the most important files to review.

Prompt for AI agents (unresolved issues)


Check if these issues are valid — if so, understand the root cause of each and fix them. If appropriate, use sub-agents to investigate and fix each issue separately.


<file name="samples/client/petstore/csharp/generichost/net10/AnyOf/src/Org.OpenAPITools/Client/ClientUtils.cs">

<violation number="1" location="samples/client/petstore/csharp/generichost/net10/AnyOf/src/Org.OpenAPITools/Client/ClientUtils.cs:333">
P2: `ContentHeaders` is missing `content-disposition`, so `IsContentHeader()` will misclassify valid multipart/file headers and route them to request headers instead of content headers.</violation>
</file>

<file name="samples/client/petstore/csharp/generichost/latest/Tags/src/Org.OpenAPITools/Client/ClientUtils.cs">

<violation number="1" location="samples/client/petstore/csharp/generichost/latest/Tags/src/Org.OpenAPITools/Client/ClientUtils.cs:344">
P2: `Content-Disposition` is missing from the content-header allowlist, so `IsContentHeader()` will misclassify a valid content header as a request header.</violation>
</file>

<file name="samples/client/petstore/csharp/generichost/net10/SourceGeneration/src/Org.OpenAPITools/Client/ClientUtils.cs">

<violation number="1" location="samples/client/petstore/csharp/generichost/net10/SourceGeneration/src/Org.OpenAPITools/Client/ClientUtils.cs:434">
P2: `ContentHeaders` allowlist is incomplete (missing `content-disposition`), so valid content headers can be misrouted to request headers.</violation>
</file>

<file name="samples/client/petstore/csharp/generichost/latest/ComposedEnum/src/Org.OpenAPITools/Client/ClientUtils.cs">

<violation number="1" location="samples/client/petstore/csharp/generichost/latest/ComposedEnum/src/Org.OpenAPITools/Client/ClientUtils.cs:324">
P1: `ContentHeaders` is missing the standard `content-disposition` content header, so `IsContentHeader()` will misclassify valid content headers and can route them to the wrong header collection.</violation>
</file>

<file name="samples/client/petstore/csharp/generichost/net10/AnyOfNoCompare/src/Org.OpenAPITools/Client/ClientUtils.cs">

<violation number="1" location="samples/client/petstore/csharp/generichost/net10/AnyOfNoCompare/src/Org.OpenAPITools/Client/ClientUtils.cs:318">
P2: `Content-Disposition` is a standard content header but is missing from the allowlist, so `IsContentHeader()` misclassifies it as a non-content header.</violation>
</file>

<file name="samples/client/petstore/csharp/generichost/latest/UseDateTimeOffset/src/Org.OpenAPITools/Client/ClientUtils.cs">

<violation number="1" location="samples/client/petstore/csharp/generichost/latest/UseDateTimeOffset/src/Org.OpenAPITools/Client/ClientUtils.cs:419">
P2: `IsContentHeader` uses an incomplete content-header allowlist and omits `content-disposition`, which can misroute that header to request headers instead of content headers.</violation>
</file>

<file name="samples/client/petstore/csharp/generichost/net10/NullReferenceTypes/src/Org.OpenAPITools/Client/ClientUtils.cs">

<violation number="1" location="samples/client/petstore/csharp/generichost/net10/NullReferenceTypes/src/Org.OpenAPITools/Client/ClientUtils.cs:434">
P1: `content-disposition` is missing from the reserved content-header allowlist, so it can still be routed to request headers instead of `HttpContent.Headers`.</violation>
</file>

<file name="samples/client/petstore/csharp/generichost/net4.7/Petstore/src/Org.OpenAPITools/Client/ClientUtils.cs">

<violation number="1" location="samples/client/petstore/csharp/generichost/net4.7/Petstore/src/Org.OpenAPITools/Client/ClientUtils.cs:432">
P2: `ContentHeaders` is missing `content-disposition`, so `IsContentHeader()` will misclassify that reserved content header and route it to the wrong header collection.</violation>
</file>

<file name="samples/client/petstore/csharp/generichost/latest/InlineEnumAnyOf/src/Org.OpenAPITools/Client/ClientUtils.cs">

<violation number="1" location="samples/client/petstore/csharp/generichost/latest/InlineEnumAnyOf/src/Org.OpenAPITools/Client/ClientUtils.cs:320">
P2: `ContentHeaders` is incomplete for `HttpContentHeaders` because it omits `content-disposition`, causing potential misclassification of a valid content header.</violation>
</file>

<file name="samples/client/petstore/csharp/generichost/net4.7/AnyOfNoCompare/src/Org.OpenAPITools/Client/ClientUtils.cs">

<violation number="1" location="samples/client/petstore/csharp/generichost/net4.7/AnyOfNoCompare/src/Org.OpenAPITools/Client/ClientUtils.cs:304">
P2: `Content-Disposition` is a valid `HttpContentHeaders` member but is missing from the content-header whitelist, so `IsContentHeader()` will misclassify it.</violation>
</file>

<file name="samples/client/petstore/csharp/generichost/net10/Petstore/src/Org.OpenAPITools/Client/ClientUtils.cs">

<violation number="1" location="samples/client/petstore/csharp/generichost/net10/Petstore/src/Org.OpenAPITools/Client/ClientUtils.cs:432">
P1: Content headers allowlist is incomplete: `content-disposition` is missing, so that header can be misclassified and routed to request headers.</violation>
</file>

<file name="samples/client/petstore/csharp/generichost/net4.7/OneOf/src/Org.OpenAPITools/Client/ClientUtils.cs">

<violation number="1" location="samples/client/petstore/csharp/generichost/net4.7/OneOf/src/Org.OpenAPITools/Client/ClientUtils.cs:328">
P2: `content-disposition` is a standard content header but is missing from the allowlist, so `IsContentHeader` will misclassify it and route it to request headers instead of `HttpContent.Headers`.</violation>
</file>

<file name="samples/client/petstore/csharp/generichost/net4.7/AnyOf/src/Org.OpenAPITools/Client/ClientUtils.cs">

<violation number="1" location="samples/client/petstore/csharp/generichost/net4.7/AnyOf/src/Org.OpenAPITools/Client/ClientUtils.cs:328">
P2: `ContentHeaders` is missing the `content-disposition` content header, so `IsContentHeader()` will misclassify a real `HttpContent` header and can route file-upload headers to the wrong collection.</violation>
</file>

<file name="samples/client/petstore/csharp/generichost/net10/FormModels/src/Org.OpenAPITools/Client/ClientUtils.cs">

<violation number="1" location="samples/client/petstore/csharp/generichost/net10/FormModels/src/Org.OpenAPITools/Client/ClientUtils.cs:428">
P2: Content header allowlist is incomplete (missing `content-disposition`), causing valid content headers to be misclassified and routed incorrectly.</violation>
</file>

<file name="samples/client/petstore/csharp/generichost/net4.7/AllOf/src/Org.OpenAPITools/Client/ClientUtils.cs">

<violation number="1" location="samples/client/petstore/csharp/generichost/net4.7/AllOf/src/Org.OpenAPITools/Client/ClientUtils.cs:328">
P2: Content header allowlist is incomplete: `content-disposition` is missing, so `IsContentHeader` can misclassify a valid content header as a request header.</violation>
</file>

<file name="samples/client/petstore/csharp/generichost/net4.7/FormModels/src/Org.OpenAPITools/Client/ClientUtils.cs">

<violation number="1" location="samples/client/petstore/csharp/generichost/net4.7/FormModels/src/Org.OpenAPITools/Client/ClientUtils.cs:428">
P2: Missing `Content-Disposition` from the reserved content-header list can misroute a valid content header to `HttpRequestMessage.Headers` instead of `HttpContent.Headers`.</violation>
</file>

<file name="samples/client/petstore/csharp/generichost/latest/OneOfList/src/Org.OpenAPITools/Client/ClientUtils.cs">

<violation number="1" location="samples/client/petstore/csharp/generichost/latest/OneOfList/src/Org.OpenAPITools/Client/ClientUtils.cs:318">
P2: `ContentHeaders` whitelist is incomplete: it omits `content-disposition`, causing valid content headers to be misclassified.</violation>
</file>

_{Reply with feedback, questions, or to request a fix. Tag @cubic-dev-ai to re-run a review.}

cubic-dev-ai

1 issue found across 37 files (changes from recent commits).

Prompt for AI agents (unresolved issues)


Check if these issues are valid — if so, understand the root cause of each and fix them. If appropriate, use sub-agents to investigate and fix each issue separately.


<file name="modules/openapi-generator/src/main/resources/csharp/libraries/generichost/api.mustache">

<violation number="1" location="modules/openapi-generator/src/main/resources/csharp/libraries/generichost/api.mustache:593">
P1: Routing content headers to `HttpRequestMessage.Content.Headers` can dereference null when the request has no body/content initialized.</violation>
</file>

_{Reply with feedback, questions, or to request a fix. Tag @cubic-dev-ai to re-run a review.}

BottlecapDave added 3 commits April 21, 2026 08:49

fix: Fixed issue where reserved headers were added to the request ins…

44a20ed

…tead of the content

fix: Fixed issue where file parameter object is incorrectly JSON seri…

78b3384

…alised

chore: Updated samples based on csharp changes

b7eee79

cubic-dev-ai Bot reviewed Apr 21, 2026

View reviewed changes

devhl-labs suggested changes Apr 22, 2026

View reviewed changes

fix: Moved content header checks to client utils

7f890c1

cubic-dev-ai Bot reviewed Apr 22, 2026

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fix: Fixed reference to new IsContentHeader static method

210df50

cubic-dev-ai Bot reviewed Apr 22, 2026

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Comment thread modules/openapi-generator/src/main/resources/csharp/libraries/generichost/api.mustache

BottlecapDave added 2 commits April 22, 2026 16:16

chore: Added "content-disposition" to content header check

99fbc55

fix: Updated ContentHeaders to be compatible with older versions of .NET

dd199ab

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wing328 commented Apr 21, 2026

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BottlecapDave commented Apr 21, 2026 •

edited by cubic-dev-ai Bot

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