Swagger payload validation not working for multiple files upload in flask

Question

I have swagger payload validation for single file upload along with json as follows:

parser = reqparse.RequestParser()
parser.add_argument('ID', type=str, required=True, location='form', help='ID is required')
parser.add_argument('name', type=str, required=True, location='form', help='name is required')
parser.add_argument('file', type=FileStorage, location='files', required=True, help='File field is required')

and flask controller for the API:

id= request.form['ID']
id= request.form['name']
file = request.files['file']

Now to upload multiple files i have added "action='append'" parameter in swagger configuration as follows:

parser = reqparse.RequestParser()
parser.add_argument('ID', type=str, required=True, location='form', help='ID is required')
parser.add_argument('name', type=str, required=True, location='form', help='name is required')
parser.add_argument('file', type=FileStorage, location='files',action='append' required=True, help='File field is required')

But while parsing

files = request.files.getlist('file')

files is None.

I can upload multiple files but stucked in swagger payload validation for multiple files. What I am doing wrong.