code: @Override
      public void associateConnection(
                                      Object connection,
                                      ManagedConnectionFactory mcf,
                                      ConnectionRequestInfo cri) throws ResourceException {
          final boolean isTraceOn = TraceComponent.isAnyTracingEnabled();
          if (isTraceOn && tc.isEntryEnabled()) {
              Tr.entry(this, tc, "associateConnection");
          }
          /*
           * Get the subject information
           */
          Subject subject = (containerManagedAuth ? getFinalSubject(cri, mcf, this) : null);
          // Give the security helper a chance to finalize what subject
          // should be used. When ThreadIdentitySupport = NOTALLOWED the
          // original subject will be unchanged.
  
          //subject = securityHelper.finalizeSubject(subject, cri, inuseCM.cmConfig);
          /*
           * Call associate connection
           */
          associateConnection(mcf, subject, cri, connection);
          if (isTraceOn && tc.isEntryEnabled()) {
              Tr.exit(this, tc, "associateConnection");
          }
      }
docs: Lazy Connection Association Optimization (smart handles)