code: public void setRollbackOnly()
      {
          if (tc.isEntryEnabled()) Tr.entry(tc, "setRollbackOnly");
  
          _rollbackOnly = true;
  
          //
          // If the LTC boundary is ActivitySession then the ActivitySession
          // is marked ResetOnly.
          //
  
          if (tc.isEntryEnabled()) Tr.exit(tc, "setRollbackOnly");
      }
docs: Marks the target LocalTransactionCoordinator such that the LTC
  will direct all enlisted resources to rollback regardless of the
  completion endMode.
  <br>If the LTC boundary is ActivitySession, then the ActivitySession
  is marked ResetOnly.