docs: public void unsubscribeResourceFor(CmsObject cms, CmsPrincipal principal, CmsResource resource)
      throws CmsException {
  
          if (!isEnabled()) {
              throw new CmsRuntimeException(Messages.get().container(Messages.ERR_SUBSCRIPTION_MANAGER_DISABLED_0));
          }
          m_securityManager.unsubscribeResourceFor(cms.getRequestContext(), getPoolName(), principal, resource);
      }