NameAbbreviator creates temporary objects

PatternLayout's NamePatternConverter and ClassNamePatternConverter delegate to NameAbbreviator.

The current API that NameAbbreviator supports is

String abbreviate(String original)

This creates temporary objects. However, the clients of NameAbbreviator already have a StringBuilder to write into. I propose to modify the NameAbbreviator API to this:

void abbreviate(String original, StringBuilder destination)