Description of change

Mark issuance date as required as implemented in the library and required by the specification.

Type of change

Choose a type of change, and delete any options that are not relevant.

• Documentation Fix

Change checklist

Tick the boxes that are relevant to your changes, and delete any items that are not.

• I have followed the contribution guidelines for this project
• I have performed a self-review of my own changes
• I have made sure that added/changed links still work
• I have commented my code, particularly in hard-to-understand areas