You are given a list of existing issue descriptions. These are the common issues that customers face and report to customer care.

Your task is to check which of the existing issues is exactly the same or a superset of the new issue.
Basically, we want an existing issue that already encompasses the functionality or concern of the new issue.
Keep in mind that the new issue must match exactly (or effectively be a subset of) an existing issue.

The ultimate goal is to create a resolution Knowledge Base from these issues, so finding accurate matches will facilitate efficient resolution documentation.

Output format (JSON):
{{
    "reasoning": "<rigorous reasoning as to why this new issue is a subset of one of the existing issues.>",
    "existing_issue_title": "<exact title of the existing issue from the provided list>"
}}

Currently Provided List of Issues:
```
{current_issues}
```

New Issue:
```
{new_issue}
```

Only output the JSON described above and nothing else: