@GetMapping("/getUserPermissionByNamespace")
    public ShenyuAdminResult getUserPermissionByNamespace(@RequestParam(name = "namespaceId", required = false) final String namespaceId) {
        PermissionMenuVO permissionMenuVO = permissionService.getPermissionMenu(namespaceId);
        return Optional.ofNullable(permissionMenuVO)
                .map(item -> ShenyuAdminResult.success(ShenyuResultMessage.MENU_SUCCESS, item))
                .orElseGet(() -> ShenyuAdminResult.error(ShenyuResultMessage.MENU_FAILED));
    }
get menu by namespace.

@param namespaceId namespace id
@return {@linkplain ShenyuAdminResult}
shenyu-admin/src/main/java/org/apache/shenyu/admin/controller/PermissionController.java