Use DateTimeFormatter.formatTo to directly append to StringBuilder

[michaelbraun]

In a few places in code, DateTimeFormatter.format(...) is called on an Instant, which creates a new String, when this is just appended to a StringBuilder. This can be improved by calling DateTimeFormatter.formatTo, passing in the StringBuilder, resulting in no intermediate String.

Checklist

• Base your changes on 2.x branch if you are targeting Log4j 2; use main otherwise
• ./mvnw verify succeeds (if it fails due to code formatting issues reported by Spotless, simply run ./mvnw spotless:apply and retry)
• Non-trivial changes contain an entry file in the src/changelog/.2.x.x directory
• Tests for the changes are provided
• Commits are signed (optional, but highly recommended)

[ppkarwasz]

@michaelbraun,

Looks good to me. Thank you for your contribution.

[michaelbraun]

@michaelbraun,

Looks good to me. Thank you for your contribution.

Does this change need a file in the changelog or additional tests before merging?

[ppkarwasz]

I don't think additional tests are needed, since your changes should be covered by the current ones.

Please add a changelog entry.

[vy]

@michaelbraun, thanks so much! 🙇
Please keep these contributions coming! 🙏