Replace usages of StringBuffer with StringBuilder
Replace usages of StringBuffer with StringBuilder

Signed-off-by: Alex Coles <60c6d277a8bd81de7fdde19201bf9c58a3df08f4@alexbcoles.com>

heitorfm/markdownj,GustavoSchroder/markdownj,myabc/markdownj,ibinti/markdown,hl198181/markdownj,magintursh/markdownj,GustavoSchroder/markdownj,myabc/markdownj,ibinti/markdown,hl198181/markdownj,magintursh/markdownj,heitorfm/markdownj