allow null metadata_array in plugin notify
allow null metadata_array in plugin notify

PeterFaiman/ruby-grpc-minimal,donnadionne/grpc,jtattermusch/grpc,zhimingxie/grpc,dgquintas/grpc,chrisdunelm/grpc,dgquintas/grpc,Vizerai/grpc,yang-g/grpc,firebase/grpc,msmania/grpc,jtattermusch/grpc,sreecha/grpc,hstefan/grpc,mehrdada/grpc,royalharsh/grpc,thunderboltsid/grpc,murgatroid99/grpc,geffzhang/grpc,philcleveland/grpc,hstefan/grpc,deepaklukose/grpc,msmania/grpc,vjpai/grpc,greasypizza/grpc,kskalski/grpc,geffzhang/grpc,apolcyn/grpc,greasypizza/grpc,jtattermusch/grpc,ncteisen/grpc,grpc/grpc,Vizerai/grpc,adelez/grpc,pszemus/grpc,nicolasnoble/grpc,soltanmm-google/grpc,quizlet/grpc,sreecha/grpc,murgatroid99/grpc,deepaklukose/grpc,firebase/grpc,kriswuollett/grpc,stanley-cheung/grpc,muxi/grpc,ctiller/grpc,ejona86/grpc,nicolasnoble/grpc,infinit/grpc,carl-mastrangelo/grpc,kumaralokgithub/grpc,soltanmm-google/grpc,pmarks-net/grpc,vjpai/grpc,simonkuang/grpc,makdharma/grpc,quizlet/grpc,muxi/grpc,7anner/grpc,pszemus/grpc,ejona86/grpc,zhimingxie/grpc,kriswuollett/grpc,yugui/grpc,donnadionne/grpc,chrisdunelm/grpc,chrisdunelm/grpc,7anner/grpc,stanley-cheung/grpc,ncteisen/grpc,kpayson64/grpc,msmania/grpc,dgquintas/grpc,LuminateWireless/grpc,rjshade/grpc,fuchsia-mirror/third_party-grpc,dklempner/grpc,msmania/grpc,rjshade/grpc,vjpai/grpc,a11r/grpc,PeterFaiman/ruby-grpc-minimal,donnadionne/grpc,kskalski/grpc,chrisdunelm/grpc,pszemus/grpc,yugui/grpc,PeterFaiman/ruby-grpc-minimal,thinkerou/grpc,ejona86/grpc,mehrdada/grpc,jboeuf/grpc,pszemus/grpc,daniel-j-born/grpc,pszemus/grpc,ctiller/grpc,donnadionne/grpc,kskalski/grpc,carl-mastrangelo/grpc,yang-g/grpc,muxi/grpc,7anner/grpc,thinkerou/grpc,ppietrasa/grpc,jboeuf/grpc,kumaralokgithub/grpc,apolcyn/grpc,msmania/grpc,mehrdada/grpc,pszemus/grpc,grani/grpc,matt-kwong/grpc,grani/grpc,PeterFaiman/ruby-grpc-minimal,greasypizza/grpc,soltanmm-google/grpc,ctiller/grpc,baylabs/grpc,hstefan/grpc,yugui/grpc,carl-mastrangelo/grpc,carl-mastrangelo/grpc,apolcyn/grpc,ncteisen/grpc,LuminateWireless/grpc,ctiller/grpc,hstefan/grpc,hstefan/grpc,hstefan/grpc,ipylypiv/grpc,stanley-cheung/grpc,ppietrasa/grpc,royalharsh/grpc,carl-mastrangelo/grpc,wcevans/grpc,Crevil/grpc,yugui/grpc,royalharsh/grpc,stanley-cheung/grpc,ppietrasa/grpc,kumaralokgithub/grpc,MakMukhi/grpc,chrisdunelm/grpc,ctiller/grpc,infinit/grpc,vjpai/grpc,donnadionne/grpc,philcleveland/grpc,vsco/grpc,infinit/grpc,soltanmm-google/grpc,nicolasnoble/grpc,dklempner/grpc,mehrdada/grpc,infinit/grpc,kpayson64/grpc,a11r/grpc,murgatroid99/grpc,grpc/grpc,nicolasnoble/grpc,thunderboltsid/grpc,ppietrasa/grpc,geffzhang/grpc,greasypizza/grpc,kpayson64/grpc,kumaralokgithub/grpc,vjpai/grpc,a11r/grpc,rjshade/grpc,kskalski/grpc,7anner/grpc,philcleveland/grpc,sreecha/grpc,firebase/grpc,mehrdada/grpc,msmania/grpc,vjpai/grpc,kriswuollett/grpc,PeterFaiman/ruby-grpc-minimal,royalharsh/grpc,Vizerai/grpc,stanley-cheung/grpc,jtattermusch/grpc,PeterFaiman/ruby-grpc-minimal,PeterFaiman/ruby-grpc-minimal,pmarks-net/grpc,royalharsh/grpc,matt-kwong/grpc,jtattermusch/grpc,infinit/grpc,murgatroid99/grpc,makdharma/grpc,matt-kwong/grpc,dklempner/grpc,zhimingxie/grpc,zhimingxie/grpc,msmania/grpc,jtattermusch/grpc,kriswuollett/grpc,zhimingxie/grpc,adelez/grpc,pmarks-net/grpc,simonkuang/grpc,wcevans/grpc,firebase/grpc,daniel-j-born/grpc,chrisdunelm/grpc,jtattermusch/grpc,kpayson64/grpc,PeterFaiman/ruby-grpc-minimal,nicolasnoble/grpc,nicolasnoble/grpc,makdharma/grpc,MakMukhi/grpc,ejona86/grpc,firebase/grpc,fuchsia-mirror/third_party-grpc,ppietrasa/grpc,MakMukhi/grpc,vjpai/grpc,Vizerai/grpc,yongni/grpc,jboeuf/grpc,LuminateWireless/grpc,rjshade/grpc,vsco/grpc,ctiller/grpc,Vizerai/grpc,ppietrasa/grpc,yugui/grpc,makdharma/grpc,msmania/grpc,greasypizza/grpc,sreecha/grpc,ncteisen/grpc,grani/grpc,vjpai/grpc,royalharsh/grpc,pmarks-net/grpc,baylabs/grpc,stanley-cheung/grpc,thinkerou/grpc,pmarks-net/grpc,rjshade/grpc,grani/grpc,greasypizza/grpc,ncteisen/grpc,rjshade/grpc,ctiller/grpc,pmarks-net/grpc,dklempner/grpc,kpayson64/grpc,sreecha/grpc,soltanmm-google/grpc,Crevil/grpc,yang-g/grpc,rjshade/grpc,vjpai/grpc,apolcyn/grpc,ppietrasa/grpc,sreecha/grpc,vsco/grpc,rjshade/grpc,daniel-j-born/grpc,stanley-cheung/grpc,carl-mastrangelo/grpc,fuchsia-mirror/third_party-grpc,thinkerou/grpc,jboeuf/grpc,kumaralokgithub/grpc,nicolasnoble/grpc,wcevans/grpc,yongni/grpc,LuminateWireless/grpc,simonkuang/grpc,zhimingxie/grpc,yang-g/grpc,MakMukhi/grpc,thunderboltsid/grpc,ncteisen/grpc,muxi/grpc,firebase/grpc,carl-mastrangelo/grpc,thinkerou/grpc,dgquintas/grpc,simonkuang/grpc,ipylypiv/grpc,adelez/grpc,donnadionne/grpc,soltanmm-google/grpc,philcleveland/grpc,deepaklukose/grpc,jtattermusch/grpc,infinit/grpc,carl-mastrangelo/grpc,Crevil/grpc,grani/grpc,firebase/grpc,nicolasnoble/grpc,firebase/grpc,grpc/grpc,ejona86/grpc,ipylypiv/grpc,adelez/grpc,ppietrasa/grpc,makdharma/grpc,kumaralokgithub/grpc,vsco/grpc,vjpai/grpc,ipylypiv/grpc,ejona86/grpc,firebase/grpc,thunderboltsid/grpc,royalharsh/grpc,quizlet/grpc,thunderboltsid/grpc,murgatroid99/grpc,grpc/grpc,geffzhang/grpc,ncteisen/grpc,LuminateWireless/grpc,ejona86/grpc,ctiller/grpc,hstefan/grpc,adelez/grpc,vsco/grpc,yongni/grpc,soltanmm-google/grpc,ipylypiv/grpc,grani/grpc,ncteisen/grpc,quizlet/grpc,thinkerou/grpc,mehrdada/grpc,mehrdada/grpc,chrisdunelm/grpc,a11r/grpc,quizlet/grpc,dgquintas/grpc,vsco/grpc,grani/grpc,daniel-j-born/grpc,greasypizza/grpc,soltanmm-google/grpc,kpayson64/grpc,deepaklukose/grpc,dgquintas/grpc,Vizerai/grpc,yugui/grpc,pszemus/grpc,nicolasnoble/grpc,philcleveland/grpc,yang-g/grpc,Crevil/grpc,thinkerou/grpc,hstefan/grpc,Vizerai/grpc,dgquintas/grpc,simonkuang/grpc,zhimingxie/grpc,stanley-cheung/grpc,jboeuf/grpc,a11r/grpc,kpayson64/grpc,dklempner/grpc,deepaklukose/grpc,thinkerou/grpc,murgatroid99/grpc,simonkuang/grpc,royalharsh/grpc,donnadionne/grpc,MakMukhi/grpc,pszemus/grpc,firebase/grpc,msmania/grpc,adelez/grpc,jtattermusch/grpc,philcleveland/grpc,apolcyn/grpc,sreecha/grpc,kpayson64/grpc,LuminateWireless/grpc,philcleveland/grpc,donnadionne/grpc,kriswuollett/grpc,jboeuf/grpc,Crevil/grpc,stanley-cheung/grpc,dgquintas/grpc,zhimingxie/grpc,chrisdunelm/grpc,PeterFaiman/ruby-grpc-minimal,simonkuang/grpc,LuminateWireless/grpc,a11r/grpc,thunderboltsid/grpc,yang-g/grpc,matt-kwong/grpc,jboeuf/grpc,grpc/grpc,kriswuollett/grpc,7anner/grpc,ipylypiv/grpc,muxi/grpc,baylabs/grpc,kpayson64/grpc,geffzhang/grpc,wcevans/grpc,jboeuf/grpc,dgquintas/grpc,greasypizza/grpc,carl-mastrangelo/grpc,sreecha/grpc,chrisdunelm/grpc,chrisdunelm/grpc,yang-g/grpc,matt-kwong/grpc,kriswuollett/grpc,philcleveland/grpc,mehrdada/grpc,LuminateWireless/grpc,ejona86/grpc,thinkerou/grpc,nicolasnoble/grpc,donnadionne/grpc,muxi/grpc,deepaklukose/grpc,ppietrasa/grpc,fuchsia-mirror/third_party-grpc,sreecha/grpc,grpc/grpc,grpc/grpc,grpc/grpc,ncteisen/grpc,thunderboltsid/grpc,rjshade/grpc,grpc/grpc,mehrdada/grpc,wcevans/grpc,yongni/grpc,simonkuang/grpc,ejona86/grpc,vjpai/grpc,carl-mastrangelo/grpc,geffzhang/grpc,matt-kwong/grpc,matt-kwong/grpc,ncteisen/grpc,mehrdada/grpc,dklempner/grpc,a11r/grpc,Crevil/grpc,pszemus/grpc,baylabs/grpc,simonkuang/grpc,adelez/grpc,yugui/grpc,fuchsia-mirror/third_party-grpc,Vizerai/grpc,pszemus/grpc,carl-mastrangelo/grpc,ipylypiv/grpc,Vizerai/grpc,zhimingxie/grpc,baylabs/grpc,Vizerai/grpc,pmarks-net/grpc,murgatroid99/grpc,thinkerou/grpc,LuminateWireless/grpc,donnadionne/grpc,dklempner/grpc,ctiller/grpc,nicolasnoble/grpc,kpayson64/grpc,pszemus/grpc,dklempner/grpc,dgquintas/grpc,apolcyn/grpc,stanley-cheung/grpc,fuchsia-mirror/third_party-grpc,apolcyn/grpc,7anner/grpc,ejona86/grpc,firebase/grpc,ejona86/grpc,adelez/grpc,mehrdada/grpc,a11r/grpc,PeterFaiman/ruby-grpc-minimal,muxi/grpc,greasypizza/grpc,ncteisen/grpc,stanley-cheung/grpc,wcevans/grpc,quizlet/grpc,ncteisen/grpc,jboeuf/grpc,pszemus/grpc,MakMukhi/grpc,grpc/grpc,thinkerou/grpc,daniel-j-born/grpc,ipylypiv/grpc,baylabs/grpc,daniel-j-born/grpc,hstefan/grpc,mehrdada/grpc,wcevans/grpc,daniel-j-born/grpc,philcleveland/grpc,fuchsia-mirror/third_party-grpc,jtattermusch/grpc,muxi/grpc,quizlet/grpc,infinit/grpc,thunderboltsid/grpc,makdharma/grpc,deepaklukose/grpc,jtattermusch/grpc,MakMukhi/grpc,ctiller/grpc,murgatroid99/grpc,vsco/grpc,murgatroid99/grpc,deepaklukose/grpc,sreecha/grpc,baylabs/grpc,fuchsia-mirror/third_party-grpc,chrisdunelm/grpc,jboeuf/grpc,geffzhang/grpc,kpayson64/grpc,yugui/grpc,ctiller/grpc,thinkerou/grpc,soltanmm-google/grpc,kumaralokgithub/grpc,vjpai/grpc,firebase/grpc,yang-g/grpc,quizlet/grpc,a11r/grpc,donnadionne/grpc,7anner/grpc,vsco/grpc,yongni/grpc,yongni/grpc,murgatroid99/grpc,grani/grpc,quizlet/grpc,kskalski/grpc,muxi/grpc,apolcyn/grpc,fuchsia-mirror/third_party-grpc,kriswuollett/grpc,infinit/grpc,MakMukhi/grpc,Crevil/grpc,carl-mastrangelo/grpc,kskalski/grpc,infinit/grpc,jboeuf/grpc,dgquintas/grpc,pmarks-net/grpc,stanley-cheung/grpc,nicolasnoble/grpc,MakMukhi/grpc,makdharma/grpc,ejona86/grpc,yang-g/grpc,kskalski/grpc,kumaralokgithub/grpc,7anner/grpc,kskalski/grpc,thunderboltsid/grpc,Crevil/grpc,yongni/grpc,adelez/grpc,grani/grpc,vsco/grpc,yongni/grpc,baylabs/grpc,Vizerai/grpc,geffzhang/grpc,jtattermusch/grpc,sreecha/grpc,ipylypiv/grpc,donnadionne/grpc,muxi/grpc,yongni/grpc,Crevil/grpc,kumaralokgithub/grpc,kskalski/grpc,muxi/grpc,sreecha/grpc,daniel-j-born/grpc,makdharma/grpc,jboeuf/grpc,baylabs/grpc,deepaklukose/grpc,matt-kwong/grpc,grpc/grpc,ctiller/grpc,royalharsh/grpc,7anner/grpc,matt-kwong/grpc,geffzhang/grpc,pmarks-net/grpc,kriswuollett/grpc,dklempner/grpc,fuchsia-mirror/third_party-grpc,makdharma/grpc,wcevans/grpc,apolcyn/grpc,daniel-j-born/grpc,grpc/grpc,wcevans/grpc,yugui/grpc,muxi/grpc