Extension additions of a SEQUENCE/SET are not set to optional

Summary

According to the ASN.1 standard, "All fields in extension additions of a SEQUENCE type or a SET type shall be transformed to optional fields". This behavior is missing currently.

Originates from this forum post: https://www.eclipse.org/forums/index.php/t/1112865/

Titan version

All

Platform details (OS type and version)

All

/cc @aknappqwt @mmagyari