Bugfixing the user picker tutorial? auiSelect2 usage

[Thomas Knight]

I'm trying to reuse some code from https://bitbucket.org/atlassian_tutorial/connect-select2-user-picker - a plugin tutorial from 2013. 

I'm able to make a simplistic sample work like on the auiSelect2 documantation, but when I run the code from Step 4 of the tutorial there's an error with this segment (key line is at "data: function"):

$userPicker.auiSelect2({
        hasAvatar: true, // auiSelect2 speciffic option, adds styling needed to properly display avatars
        multiple: true, // make the control a multi-select
        ajax: {
            url: "/rest/api/2/user/picker", // JIRA-relative URL to the REST end-point
            type: "GET",
            dataType: 'json',
            cache: true,
            // query parameters for the remote ajax call
            data: function data(term) {
                return {
                    query: term,
                    maxResults: 1000,
                    showAvatar: true
                };
            },

 Error message:

Encountered \"data\" at /templates/assign/editAssign.vm[line 43, column 36]\nWas expecting one of:\n    \",\" ...\n    \"}\" ...\n    \"}\"

This suggests the ajax part is malformed, but I'm not sure why or how to fix it. Is this indicative of another problem?

I've already had to remove //comments to prevent error.

[Thomas Knight · Accepted solution]

Self-solved: was using .vm files, or Apache Velocity. While this works fine with $.whatever variables like in other samples I used, it does not work with $whatever variables - like $userPicker. The line quoted in the error is a red herring.