How to change priority of WTForms validators?

Question

tl;dr: I need to change the order in which WTForms validators validate the user input. How do I do that?

Details:

Flask code:

class SampleForm(Form):
    user_email = user_email_field
...
@api.route('/sample-route')
class ClassName(Resource):
    @api.expect(sample_payload)
    @api.marshal_with(sample_response)
    def post(self):
        form = SampleForm(formdata=MultiDict(api.payload))
        if not form.validate():
            return {"form_errors": form.errors}, 400
        ...

WTForms validation field:

user_email_field = EmailField('Email Address',[
    validators.InputRequired(Errors.REQUIRED_FIELD),
    validators.Length(min=5, max=256),
    validators.Email(Errors.INVALID_EMAIL_ADDRESS),
])

Problem is, user_email is checked by validators in the wrong order. I send a request with the following body:

{
  "user_email": ""
}

I get this response:

{
  "form_errors": {
    "user_email": [
      "'' is too short"
    ]
  }
}

As you see, despite being 2nd in the list of validators, validators.Length() kicks in before everything else.

If I comment it out in the validation field like that:

user_email_field = EmailField('Email Address',[
    validators.InputRequired(Errors.REQUIRED_FIELD),
    # validators.Length(min=5, max=256),
    validators.Email(Errors.INVALID_EMAIL_ADDRESS),
])

then the exact same request will yield a desired response:

{
  "errors": null,
  "success": null,
  "form_errors": {
    "user_email": [
      "REQUIRED_FIELD"
    ]
  }
}

However, this is not a working solution because, of course, then eMail won't be checked for its length.

Question:

How do I change the priority of these validators? How do I make WTForms always check the user input with validators.InputRequired() FIRST and with validators.Length() SECOND and not the other way around?