@Override
  public final void preTearDown() throws Exception {
    VM vm0 = Host.getHost(0).getVM(0);
    vm0.invoke(IdleTimeOutDUnitTest::closeCache);
  }
Return file as string and then modify the string accordingly **
geode-core/src/distributedTest/java/org/apache/geode/internal/jta/dunit/IdleTimeOutDUnitTest.java