@Override
      public Object call() throws Exception {
        final Region r = getCache().getRegion(REP_REG_NAME);
        final Region pr = getCache().getRegion(PR_REG_NAME);
        assertNull(r.putIfAbsent("key0", "value"));
        assertNull(pr.putIfAbsent("key0", "value"));
        assertNull(r.putIfAbsent("keyForClient", "value"));
        assertNull(pr.putIfAbsent("keyForClient", "value"));
        assertEquals("value", r.putIfAbsent("key0", "value2"));
        assertEquals("value", pr.putIfAbsent("key0", "value2"));
        return null;
      }
tests for the concurrentMapOperations. there are more tests in ClientServerMiscDUnitTest
geode-core/src/distributedTest/java/org/apache/geode/internal/cache/ConcurrentMapOpsDUnitTest.java