docs: public synchronized boolean undoRoleMappingRemove(final Object removalKey) {
          HashMap<String, RoleMappingImpl> newRoles = new HashMap<String, RoleMappingImpl>(roleMappings);
          RoleMappingImpl toRestore = removedRoles.remove(removalKey);
          if (toRestore != null && newRoles.containsKey(toRestore.getName()) == false) {
              newRoles.put(toRestore.getName(), toRestore);
              roleMappings = Collections.unmodifiableMap(newRoles);
              return true;
          }
  
          return false;
      }