Find a specific {@link Ext.form.field.Field} in this form by id or name.
@param {String} id The value to search for (specify either a {@link Ext.Component#id id} or
{@link Ext.form.field.Field#getName name or hiddenName}).
@return {Ext.form.field.Field} The first matching field, or `null` if none was found.
function(id) {
        return this.getFields().findBy(function(f) {
            return f.id === id || f.getName() === id;
        });
    }