Substitution plugins implement the method getUrl(). This is how LinkIt gets the value for attribute "href" of the resulting <a> element.
Some substitution plugins may want to add more attributes to the resulting <a> element.
See official (HTML5) attributes and also consider "data-*" attributes.
LinkIt does not allow this today.
I wish it would.
Needs work
5.0
Code
Not all content is available!
It's likely this issue predates Contrib.social: some issue and comment data are missing.