Use non synchronized version StringBuilder instead of StringBuffer
Use non synchronized version StringBuilder instead of StringBuffer

git-svn-id: https://svn.apache.org/repos/asf/jmeter/trunk@1722354 13f79535-47bb-0310-9956-ffa450edef68

Former-commit-id: 89f9a36825fbbd2d3e01151001e2907bcd928683
benbenw/jmeter,apache/jmeter,ham1/jmeter,apache/jmeter,ham1/jmeter,benbenw/jmeter,etnetera/jmeter,apache/jmeter,apache/jmeter,etnetera/jmeter,ham1/jmeter,benbenw/jmeter,etnetera/jmeter,etnetera/jmeter,ham1/jmeter,apache/jmeter,etnetera/jmeter,ham1/jmeter,benbenw/jmeter