code: protected boolean matchBranchCoupling(int couplingType1, int couplingType2, ManagedConnectionFactory managedConnectionFactory) {
          final boolean isTraceOn = TraceComponent.isAnyTracingEnabled();
          boolean matched = true;
          if (isJDBC && couplingType1 != couplingType2) {
              // ResourceRefInfo.BRANCH_COUPLING_UNSET can default to BRANCH_COUPLING_TIGHT or BRANCH_COUPLING_LOOSE
              if (couplingType1 == ResourceRefInfo.BRANCH_COUPLING_UNSET)
                  couplingType1 = ((WSManagedConnectionFactory) managedConnectionFactory).getDefaultBranchCoupling();
              else if (couplingType2 == ResourceRefInfo.BRANCH_COUPLING_UNSET)
                  couplingType2 = ((WSManagedConnectionFactory) managedConnectionFactory).getDefaultBranchCoupling();
              matched = couplingType1 == couplingType2;
          }
          if (isTraceOn && tc.isDebugEnabled()) {
              Tr.debug(this, tc, "Match coupling request for " + couplingType1 + " and " + couplingType2 + " match is " + matched);
          }
          return matched;
      }
docs: May be called if couplingType indicates LOOSE or TIGHT or is UNSET