code: @Nullable
    public DATATYPE getIfFailure (@Nullable final DATATYPE aSuccessValue)
    {
      return m_eSuccess.isFailure () ? m_aObj : aSuccessValue;
    }
docs: Get the store value if this is a failure. Otherwise the passed success
  value is returned.
  
  @param aSuccessValue
  The failure value to be used. May be <code>null</code>.
  @return Either the stored value or the failure value. May be
  <code>null</code>.