Use it without the ONLINE option:

ANALYZE INDEX "ADR2~I01" VALIDATE STRUCTURE;

As per oracle documentation, when you perform "ANALYZE... VALIDATE STRUCTURE ONLINE", no statistics are gathered, the process only validates the integrity of the object:
When you validate the structure of an object ONLINE, Oracle does not collect any statistics, as it does when you validate the structure of the object OFFLINE
.

Regarding the question about where to get various index statistics from: You can get all of them (except del_lf_rows) in DBA_/ALL_USER_INDEXES. You must of course first collect those statistics either with ANALYZE command or (preferebly) by using DBMS_STATS.