docs: @Override
      public String getRealm() {
          try {
              String realmName = customUserRegistry.getRealm();
              if (realmName == null || realmName.trim().isEmpty()) {
                  realmName = CUSTOM_REALM;
              }
              return realmName;
          } catch (Exception e) {
              if (TraceComponent.isAnyTracingEnabled() && tc.isDebugEnabled()) {
                  Tr.debug(tc, "Exception caught on getRealm", customUserRegistry, e);
              }
          }
          return DEFAULT_REALM;
      }