code: public boolean isUnknown(Object value)
  	{
  		return value == null || (value instanceof Set ? ((Set) value).isEmpty() : false);
  	}
docs: Checks if the <em>value</em> is unkown. In this context a <em>value</em> is regarded to be
  unknown if it is null (unset).
  @param value the value to be checked
  @return true if the value is unknown