VM rollLocatorToCurrent(VM rollLocator, final String serverHostName, final int port,
      final String testName, final String locatorString) {
    // Roll the locator
    rollLocator.invoke(invokeStopLocator());
    VM newLocator = Host.getHost(0).getVM(VersionManager.CURRENT_VERSION, rollLocator.getId());
    newLocator.invoke(invokeStartLocator(serverHostName, port, testName,
        getLocatorProperties(locatorString), false));
    return newLocator;
  }
This test starts up multiple servers from the current code base and multiple servers from the
old version and executes puts and gets on a new server and old server and verifies that the
results are present. Note that the puts have overlapping region keys just to test new puts and
replaces
geode-core/src/upgradeTest/java/org/apache/geode/internal/cache/rollingupgrade/RollingUpgrade2DUnitTestBase.java