@Override
  public synchronized void toData(DataOutput out) throws IOException {
    mergeBitSet();
    InternalDataSerializer.writeUnsignedVL(version, out);
    int size = (exceptions == null) ? 0 : exceptions.size();
    InternalDataSerializer.writeUnsignedVL(size, out);
    out.writeBoolean(isDepartedMember);
    if (size > 0) {
      for (RVVException e : exceptions) {
        InternalDataSerializer.invokeToData(e, out);
      }
    }
  }
returns true if this holder has seen versions that the other holder hasn't
geode-core/src/main/java/org/apache/geode/internal/cache/versions/RegionVersionHolder.java