Problem:

The standard Javascript function Date.prototype.setFullYear gets overwritten by the "jira.webresources:calendar-lib" (file: Calendar.js) module in such a fashion that it breaks any other javascript code or framework that depends on its original behavior of the function.

This is a non-standard practice and should be deprecated by Jira.

Plugin developers spend lots of time trying to figure out a workaround to be able to access the original method.

Workaround:

The original behavior of Date.prototype.setFullYear is saved in Date.prototype.__msh_oldSetFullYear so the user can just reassign the original value in his script.