code: public boolean hasSingleOptionalValue() {
  
          return ((getEntityType().getAttributeMinOccurrence(m_attributeName) == 0)
              && (m_entity.getAttribute(m_attributeName) != null)
              && (m_entity.getAttribute(m_attributeName).getValueCount() == 1));
      }
docs: Return true if there is a single remaining value, which is optional.<p>
  
  @return true if this has only one optional value