Fix the boundary quotation, was using the wrong option

src/RestSharp/Request/RequestContent.cs

@@ -203,7 +203,7 @@ class RequestContent : IDisposable {
 
         string GetContentTypeHeader(string contentType)
             => Content is MultipartFormDataContent
-                ? $"{contentType}; boundary={GetBoundary(GetOrSetFormBoundary(), _request.MultipartFormQuoteParameters)}"
+                ? $"{contentType}; boundary={GetBoundary(GetOrSetFormBoundary(), _request.MultipartFormQuoteBoundary)}"
                 : contentType;
     }
 

src/RestSharp/Request/RestRequest.cs

@@ -82,11 +82,17 @@ public RestRequest(Uri resource, Method method = Method.Get)
     public bool AlwaysMultipartFormData { get; set; }
 
     /// <summary>
-    /// When set to true, parameters in a multipart form data requests will be enclosed in
+    /// When set to true, parameter values in a multipart form data requests will be enclosed in
     /// quotation marks. Default is false. Enable it if the remote endpoint requires parameters
     /// to be in quotes (for example, FreshDesk API). 
     /// </summary>
-    public bool MultipartFormQuoteParameters { get; set; } = true;
+    public bool MultipartFormQuoteParameters { get; set; }
+
+    /// <summary>
+    /// When set to true, the form boundary part of the content type will be enclosed in
+    /// quotation marks. Default is true.
+    /// </summary>
+    public bool MultipartFormQuoteBoundary { get; set; } = true;
 
     /// <summary>
     /// Overrides the default (random) form boundary

test/RestSharp.Tests.Integrated/MultipartFormDataTests.cs

@@ -83,7 +83,7 @@ static class RequestHandler {
         var request = new RestRequest("/", Method.Post) { AlwaysMultipartFormData = true };
 
         AddParameters(request);
-        request.MultipartFormQuoteParameters = false;
+        request.MultipartFormQuoteBoundary = false;
 
         var response = await _client.ExecuteAsync(request);