I want to get value from username fieldname in User doctype that use in options:"" in filters

fieldname: “submitted_by”,
label: “Submitted By”,
fieldtype: “Link”,
options: “User”,
default: “”,
get_query: function() {
return {
query: “frappe.core.doctype.user.user.user_query”,
filters: {
enabled: 1
fieldname: “username” // Specify the fieldname for display
It show me gmail of user, But I want to show username of user. please help me. And sorry for my bad english