Fix cpu info in hypervisor

[zizhongwei]

Fix cpu info in hypervisor for #1012

[auhlig]

Hi @zizhongwei,
Thanks for the PR.
Could you wrap some test around that? Why are you using List<Object>?

[zizhongwei]

there is a note in the openstack api description:
Since version 2.28 cpu_info field is returned as a dictionary instead of string.
When I use the Hypervisor list api to get the hypervisors,it returned a JSON like this：
"cpu_info": {"model": ["Intel(R)Xeon(R)CPUE5-2620v2@2.10GHz"], "vendor": ["GenuineIntel"], "nodes": 1, "topology": {"cores": 12, "threads": 24}}
in this JSON, "model" field is ["Intel(R)Xeon(R)CPUE5-2620v2@2.10GHz"] and "vendor" field is ["GenuineIntel"].
In my test the Jackson can reads this "model" field to List<Object>(can not reads this "model" field to String)
and the Jackson can also reads JSON "model": "Intel(R)Xeon(R)CPUE5-2620v2@2.10GHz" to List<Object>，
so I replaced String with List<Object>

[auhlig]

Wouldn't​ List<Object> be incompatible with the json-string, whereas the type string would work for both?

[zizhongwei]

openstack4j has used Jackson read json to java Object.
Jackson can read json-string :"model": "Intel(R)Xeon(R)CPUE5-2620v2@2.10GHz" to List<Object>, also can read json :"model": ["Intel(R)Xeon(R)CPUE5-2620v2@2.10GHz"] to List<Object>;
Jackson can not read json :"model": ["Intel(R)Xeon(R)CPUE5-2620v2@2.10GHz"] to String ,will throw a exception like : #1012

[auhlig]

I see. LGTM. Thanks @zizhongwei