message: Fix duplicate content-type in server response
diff: @@ -492,6 +492,21 @@ private class ServerHttpProtocolImplGenerator(
  * The `Content-Type` header is also set according to the protocol and the contents of the shape to be serialized.
  */
  private fun RustWriter.serverRenderResponseHeaders(operationShape: OperationShape, errorShape: StructureShape? = null) {
  + val bindingGenerator = ServerResponseBindingGenerator(protocol, codegenContext, operationShape)
  + val addHeadersFn = bindingGenerator.generateAddHeadersFn(errorShape ?: operationShape)
  + if (addHeadersFn != null) {
  + // notice that we need to borrow the output only for output shapes but not for error shapes
  + val outputOwnedOrBorrow = if (errorShape == null) "&output" else "output"
  + rust(
  + """
  + builder = #{T}($outputOwnedOrBorrow, builder)?;
  + """.trimIndent(),
  + addHeadersFn
  + )
  + }
  +
  + // set the content type header *after* the response bindings headers have been set
  + // to allow operations that bind a member to content-type to take precedence
  val contentType = httpBindingResolver.responseContentType(operationShape)
  if (contentType != null) {
  rustTemplate(
  @@ -505,19 +520,6 @@ private class ServerHttpProtocolImplGenerator(
  *codegenScope
  )
  }
  -
  - val bindingGenerator = ServerResponseBindingGenerator(protocol, codegenContext, operationShape)
  - val addHeadersFn = bindingGenerator.generateAddHeadersFn(errorShape ?: operationShape)
  - if (addHeadersFn != null) {
  - // notice that we need to borrow the output only for output shapes but not for error shapes
  - val outputOwnedOrBorrow = if (errorShape == null) "&output" else "output"
  - rust(
  - """
  - builder = #{T}($outputOwnedOrBorrow, builder)?;
  - """.trimIndent(),
  - addHeadersFn
  - )
  - }
  }
  private fun serverRenderBindingSerializer(
  