Remove useless null test use parseBoolean
Remove useless null test
use parseBoolean

git-svn-id: https://svn.apache.org/repos/asf/jmeter/trunk@1380366 13f79535-47bb-0310-9956-ffa450edef68

Former-commit-id: 2f07fb0140171a34255404ca19330212c5581079
etnetera/jmeter,benbenw/jmeter,ham1/jmeter,apache/jmeter,apache/jmeter,ham1/jmeter,benbenw/jmeter,apache/jmeter,etnetera/jmeter,etnetera/jmeter,benbenw/jmeter,ham1/jmeter,apache/jmeter,ham1/jmeter,ham1/jmeter,etnetera/jmeter,benbenw/jmeter,etnetera/jmeter,apache/jmeter