Spring Replace use of StringBuffer with StringBuilder

Comment From: sbrannen

I was thinking we'd already gotten rid of StringBuffer usage in favor of StringBuilder, but those two methods were still forced to stick with StringBuffer on JDK 8.

With JDK 9, java.util.regex.Matcher received overloaded variants of appendReplacement() and appendTail that accept a StringBuilder. 👍

Good catch!

Comment From: sbrannen

This has been merged into main.

Thanks