public static Object put(GemFireCache cache, String regionName, Object key, Object value) {
    Region region = getRegion(cache, regionName);
    System.out.println(regionName + ".put(" + key + "," + value + ")");
    Object result = region.put(key, value);
    System.out.println("returned " + result);
    return result;
  }
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