Kong：如何按服务列出路由并限制大小？

我正在尝试列出所有的服务路由并限制返回的大小：

"GET /services/get-headers/routes?size=3 HTTP/1.1", host: "localhost:8001"

但是我收到一个错误，说：

/usr/local/share/lua/5.1/kong/api/endpoints.lua:122: size must be a number

我相当确定这是一个 bug，但我不太了解 Lua，无法调试 Kong 源代码。有谁知道我该如何实现这个功能吗？

完整的堆栈跟踪:

2018/09/23 16:07:35 [error] 64#0: *1056076 lua coroutine: runtime error: /usr/local/share/lua/5.1/kong/api/endpoints.lua:122: size must be a number
stack traceback:
coroutine 0:
    [C]: in function 'error'
    /usr/local/share/lua/5.1/kong/db/dao/init.lua:48: in function </usr/local/share/lua/5.1/kong/db/dao/init.lua:41>
    /usr/local/share/lua/5.1/kong/api/endpoints.lua:122: in function </usr/local/share/lua/5.1/kong/api/endpoints.lua:111>
coroutine 1:
    [C]: in function 'resume'
    /usr/local/share/lua/5.1/lapis/application.lua:393: in function 'handler'
    /usr/local/share/lua/5.1/lapis/application.lua:130: in function 'resolve'
    /usr/local/share/lua/5.1/lapis/application.lua:161: in function </usr/local/share/lua/5.1/lapis/application.lua:159>
    [C]: in function 'xpcall'
    /usr/local/share/lua/5.1/lapis/application.lua:159: in function 'dispatch'
    /usr/local/share/lua/5.1/lapis/nginx.lua:215: in function 'serve_admin_api'
    content_by_lua(nginx-kong.conf:175):2: in function <content_by_lua(nginx-kong.conf:175):1>, client: 172.22.0.1, server: kong_admin, request: "GET /services/get-headers/routes?size=3 HTTP/1.1", host: "localhost:8001"