This function is
EXPERIMENTAL. The behaviour of this function, the
name of this function, and anything else documented about this
function may change without notice in a future release of PHP.
Use this function at your own risk.
Get the data object which contains this data object.
Returns the SDO_DataObject which contains this SDO_DataObject,
or returns NULL if this is a root SDO_DataObject
(i.e. it has no container).