[MISC 4/4] distinguish nil and empty map
[MISC 4/4] distinguish nil and empty map

Since the function len(X) will return 0 no matter X is nil or
an empty map.

We should distinguish that.

Signed-off-by: Hu Keping <ce660952c949ad2751377b45317337be332e80ac@huawei.com>

shin-/docker.github.io,docker/docker.github.io,menglingwei/denverdino.github.io,jzwlqx/denverdino.github.io,joaofnfernandes/docker.github.io,LuisBosquez/docker.github.io,JimGalasyn/docker.github.io,troy0820/docker.github.io,dqminh/notary,JimGalasyn/docker.github.io,danix800/docker.github.io,shubheksha/docker.github.io,denverdino/docker.github.io,endophage/notary,jzwlqx/denverdino.github.io,bdwill/docker.github.io,gdevillele/docker.github.io,johnstep/docker.github.io,HuKeping/notary,LuisBosquez/docker.github.io,rillig/docker.github.io,cyli/notary,shubheksha/docker.github.io,BSWANG/denverdino.github.io,umayr/notary,menglingwei/denverdino.github.io,thaJeztah/docker.github.io,johnstep/docker.github.io,docker/docker.github.io,londoncalling/docker.github.io,joaofnfernandes/docker.github.io,danix800/docker.github.io,anweiss/docker.github.io,alexisbellido/docker.github.io,bdwill/docker.github.io,docker/notary,denverdino/denverdino.github.io,thaJeztah/docker.github.io,andrewhsu/notary,alexisbellido/docker.github.io,aduermael/docker.github.io,jfrazelle/notary,sanscontext/docker.github.io,thaJeztah/docker.github.io,johnsandiford/notary,sanscontext/docker.github.io,docker/docker.github.io,docker-zh/docker.github.io,cyli/notary,gdevillele/docker.github.io,joaofnfernandes/docker.github.io,LuisBosquez/docker.github.io,JimGalasyn/docker.github.io,londoncalling/docker.github.io,joaofnfernandes/docker.github.io,anweiss/docker.github.io,anweiss/docker.github.io,londoncalling/docker.github.io,londoncalling/docker.github.io,LuisBosquez/docker.github.io,bdwill/docker.github.io,shubheksha/docker.github.io,cyli/notary,LuisBosquez/docker.github.io,jzwlqx/denverdino.github.io,docker/docker.github.io,menglingwei/denverdino.github.io,docker/notary,johnsandiford/notary,aduermael/docker.github.io,bdwill/docker.github.io,JimGalasyn/docker.github.io,phiroict/docker,sanscontext/docker.github.io,alexisbellido/docker.github.io,BSWANG/denverdino.github.io,danix800/docker.github.io,joeuo/docker.github.io,JimGalasyn/docker.github.io,denverdino/docker.github.io,dqminh/notary,docker-zh/docker.github.io,dqminh/notary,phiroict/docker,shin-/docker.github.io,vdemeester/notary,anweiss/docker.github.io,sanscontext/docker.github.io,phiroict/docker,anweiss/docker.github.io,docker/notary,danix800/docker.github.io,andrewhsu/notary,shubheksha/docker.github.io,troy0820/docker.github.io,rillig/docker.github.io,denverdino/denverdino.github.io,jzwlqx/denverdino.github.io,alexisbellido/docker.github.io,joeuo/docker.github.io,HuKeping/notary,johnstep/docker.github.io,johnstep/docker.github.io,denverdino/denverdino.github.io,bdwill/docker.github.io,BSWANG/denverdino.github.io,shubheksha/docker.github.io,rillig/docker.github.io,BSWANG/denverdino.github.io,sanscontext/docker.github.io,troy0820/docker.github.io,aduermael/docker.github.io,aduermael/docker.github.io,shin-/docker.github.io,menglingwei/denverdino.github.io,jfrazelle/notary,umayr/notary,joaofnfernandes/docker.github.io,docker-zh/docker.github.io,thaJeztah/docker.github.io,docker-zh/docker.github.io,andrewhsu/notary,johnsandiford/notary,endophage/notary,londoncalling/docker.github.io,rillig/docker.github.io,thaJeztah/docker.github.io,shin-/docker.github.io,docker/docker.github.io,shin-/docker.github.io,denverdino/docker.github.io,denverdino/docker.github.io,docker-zh/docker.github.io,vdemeester/notary,troy0820/docker.github.io,gdevillele/docker.github.io,phiroict/docker,joeuo/docker.github.io,denverdino/denverdino.github.io,BSWANG/denverdino.github.io,umayr/notary,gdevillele/docker.github.io,denverdino/docker.github.io,jzwlqx/denverdino.github.io,johnstep/docker.github.io,denverdino/denverdino.github.io,endophage/notary,joeuo/docker.github.io,alexisbellido/docker.github.io,phiroict/docker,menglingwei/denverdino.github.io,jfrazelle/notary,vdemeester/notary,gdevillele/docker.github.io,HuKeping/notary,joeuo/docker.github.io