public boolean getReadOldValueFromDisk() {
    return readOldValueFromDisk;
  }
If true then when getOldValue is called if the NOT_AVAILABLE is found then an attempt will be
made to read the old value from disk without faulting it in. Should only be set to true when
product is calling a method on a CacheWriter.
geode-core/src/main/java/org/apache/geode/internal/cache/EntryEventImpl.java