Adds request_body_multipart method which enables schema properties to be written for multipart upload body

Will inspect the provided hash and add the property file_name to the parameters collection so upload and 3.0 output will work properly

test-app/spec/integration/blogs_spec.rb

@@ -65,7 +65,7 @@ describe 'Blogs API', type: :request, swagger_doc: 'v1/swagger.json' do
       description 'Retrieves a specific blog by id'
       operationId 'getBlog'
       produces 'application/json'
-      
+
       parameter name: :id, in: :path, type: :string
 
       response '200', 'blog found' do
@@ -106,7 +106,9 @@ describe 'Blogs API', type: :request, swagger_doc: 'v1/swagger.json' do
       description 'Upload a thumbnail for specific blog by id'
       operationId 'uploadThumbnailBlog'
       consumes 'multipart/form-data'
-      parameter name: :file, in: :formData, type: :file, required: true
+      # parameter name: :file, in: :formData, type: :file, required: true
+
+      request_body_multipart schema: {properties: {:orderId => { type: :integer }, file: { type: :string, format: :binary }} }
 
       response '200', 'blog updated' do
         let(:file) { Rack::Test::UploadedFile.new(Rails.root.join('spec/fixtures/thumbnail.png')) }
@@ -115,3 +117,4 @@ describe 'Blogs API', type: :request, swagger_doc: 'v1/swagger.json' do
     end
   end
 end
+

test-app/swagger/v1/swagger.json

@@ -177,14 +177,6 @@
             "schema": {
               "type": "string"
             }
-          },
-          {
-            "name": "file",
-            "in": "formData",
-            "required": true,
-            "schema": {
-              "type": "file"
-            }
           }
         ],
         "tags": [
@@ -192,6 +184,23 @@
         ],
         "description": "Upload a thumbnail for specific blog by id",
         "operationId": "uploadThumbnailBlog",
+        "requestBody": {
+          "content": {
+            "multipart/form-data": {
+              "schema": {
+                "properties": {
+                  "orderId": {
+                    "type": "integer"
+                  },
+                  "file": {
+                    "type": "string",
+                    "format": "binary"
+                  }
+                }
+              }
+            }
+          }
+        },
         "responses": {
           "200": {
             "description": "blog updated"