public void setOldValueFromRegion() {
    try {
      RegionEntry re = getRegion().getRegionEntry(getKey());
      if (re == null) {
        return;
      }
      ReferenceCountHelper.skipRefCountTracking();
      Object v = re.getValueRetain(getRegion(), true);
      if (v == null) {
        v = Token.NOT_AVAILABLE;
      }
      ReferenceCountHelper.unskipRefCountTracking();
      try {
        setOldValue(v);
      } finally {
        if (mayHaveOffHeapReferences()) {
          OffHeapHelper.releaseWithNoTracking(v);
        }
      }
    } catch (EntryNotFoundException ignore) {
    }
  }
The size the new value contributes to a pr bucket. Note if this event is not on a pr then this
value will be 0.
geode-core/src/main/java/org/apache/geode/internal/cache/EntryEventImpl.java