code: @Override
      public boolean isSubjectValid(Subject subject) {
          boolean isValid = true;
          // Step through the list of registered providers
          Iterator<CredentialProvider> itr = credentialProviders.getServices();
          while (itr.hasNext()) {
              CredentialProvider provider = itr.next();
              isValid = isValid && provider.isSubjectValid(subject);
              //TODO - JwtSSOToken fallback to LTPA
              if (!isValid) {
                  break;
              }
          }
          return isValid;
      }
docs: {@inheritDoc}