となります。 _owner が nullの場合は "" を返します。
This method returns a string which specifies the object uniquely. The string which AbsName returns will be created by concatenating
"absolute name of the owner"
"/"
_objectName
"__"
_objectNumber.
When _owner == NULL, "absolute name of the owner" is taken as "".
Assume that the absolute name of the owner is "/total_sytetem__0", _objectName of the current object is "elm_t", and _objectNumber is 0, then "absname" is