public synchronized long verifyBeginUpdateMemoryUsed(boolean expected_willSendEvent) {
      if (!beginUpdateMemoryUsed) {
        fail("beginUpdateMemoryUsed was not called");
      }
      assertEquals(expected_willSendEvent, beginUpdateMemoryUsed_willSendEvent);
      return beginUpdateMemoryUsed_bytesUsed;
    }
Verify that beginUpdateMemoryUsed was called, event will be sent, and return the "bytesUsed"
it recorded.
geode-core/src/distributedTest/java/org/apache/geode/cache/management/MemoryThresholdsOffHeapDUnitTest.java