fix(generic_json_gen): inconsistent attributes value

Description

fix(generic_json_gen): inconsistent attributes value

• attributes will now replace all null values with an empty object

How to test

Running generic_json_gen locally and checking if the values contain nulls.

Author's checklist

• I have followed the contribution guidelines
• This MR has been tested or does not change functionality
• I have added relevant merge request dependencies (if this MR has any)
• I have added the correct labels
• I have assigned reviewers (if any are relevant)
• I have edited the documentation (if the changes require it) or I have noted the need for the change if I do not have access to the documentation
• I have marked all introduced BREAKING CHANGES or necessary DEPLOYMENT NOTES in the commit message(s)

Reviewer's checklist

• This MR has been tested or does not change functionality
• This MR has correct commit message format

Related issues

Closes STR-1174