How to fill field with username in JIRA Service Desk?

Question

Java

It is necessary to make a field in the template for creating an application / incident, which was automatically filled in with user data, or rather, with his login.
Those. the user logged into the system under 11-zyi
Creates an incident, and the field in the template is already filled with his login (11-zyi) and even onlyread
Any ideas? Can you recommend a plugin or a script for the text field (and where to shove this script?)?