Specify a Content-Type header on stream type requests when th epayload type is known

src/SwaggerProvider.DesignTime/v3/OperationCompiler.fs

@@ -358,7 +358,7 @@ type OperationCompiler(schema: OpenApiDocument, defCompiler: DefinitionCompiler,
                                 <@
                                     let stream: obj = %%streamObj
                                     let msg = %httpRequestMessage
-                                    msg.Content <- RuntimeHelpers.toStreamContent(stream)
+                                    msg.Content <- RuntimeHelpers.toStreamContent(stream, payloadMime)
                                     msg
                                 @>
                             | Some(MultipartFormData, formData) ->

src/SwaggerProvider.Runtime/RuntimeHelpers.fs

@@ -2,6 +2,7 @@ namespace Swagger.Internal
 
 open System
 open System.Net.Http
+open System.Net.Http.Headers
 open System.Text.Json.Serialization
 open System.Threading.Tasks
 
@@ -133,9 +134,15 @@ module RuntimeHelpers =
     let toTextContent(valueStr: string) =
         new StringContent(valueStr, Text.Encoding.UTF8, "text/plain")
 
-    let toStreamContent(boxedStream: obj) =
+    let toStreamContent(boxedStream: obj, contentType: string) =
         match boxedStream with
-        | :? IO.Stream as stream -> new StreamContent(stream)
+        | :? IO.Stream as stream ->
+            let content = new StreamContent(stream)
+
+            if (not <| String.IsNullOrEmpty(contentType)) then
+                content.Headers.ContentType <- MediaTypeHeaderValue(contentType)
+
+            content
         | _ -> failwith $"Unexpected parameter type {boxedStream.GetType().Name} instead of IO.Stream"
 
     let getPropertyValues(object: obj) =

tests/Swashbuckle.WebApi.Server/Controllers/FileController.fs

@@ -52,9 +52,13 @@ type ReturnFileController() =
     [<HttpPost("stream"); BinaryContent>]
     member this.GetFileLength() =
         task {
-            use reader = new StreamReader(this.Request.Body)
-            let! content = reader.ReadToEndAsync()
-            return content.Length
+
+            if this.Request.ContentType <> "application/octet-stream" then
+                return ActionResult<int>(UnsupportedMediaTypeResult())
+            else
+                use reader = new StreamReader(this.Request.Body)
+                let! content = reader.ReadToEndAsync()
+                return ActionResult<int>(this.Ok(content.Length))
         }
 
     [<HttpPost("single"); Produces(MediaTypes.ApplicationOctetStream, Type = typeof<FileResult>)>]