Inconsistency in formData and json payloads

[mikemellor11]

Json payload

// Form
form: new Form({
    title: undefined,
    file: null
});

// Request
this.form.post('/api/post');

// Actual Payload
{
    file: null
}

Form data payload

// Form
form: new Form({
    title: undefined,
    file: File
});

// Request
this.form.post('/api/post');

// Actual Payload
{
    title: undefined
    file: Binary
}

JSON.stringify is automatically removing undefined properties from the string sent to the server, shouldn't the form data match this?