[RELEASE] -  publish version:  '1.2.1-rc20'.
[RELEASE] -  publish version:  '1.2.1-rc20'.

betable/zipkin,mt0803/zipkin,betable/zipkin,jstanier/zipkin,prat0318/zipkin,wuqiangxjtu/zipkin,Yelp/zipkin,thelastpickle/zipkin,jstanier/zipkin,thelastpickle/zipkin,mt0803/zipkin,jamescway/zipkin,coursera/zipkin,jfeltesse-mdsol/zipkin,Yelp/zipkin,coursera/zipkin,jstanier/zipkin,betable/zipkin,mt0803/zipkin,jfeltesse-mdsol/zipkin,hydro2k/zipkin,lqjack/zipkin,jstanier/zipkin,prat0318/zipkin,srijs/zipkin,prat0318/zipkin,thelastpickle/zipkin,wuqiangxjtu/zipkin,lqjack/zipkin,srijs/zipkin,coursera/zipkin,hydro2k/zipkin,thelastpickle/zipkin,rocwzp/zipkin,rjbhewei/zipkin,rocwzp/zipkin,rjbhewei/zipkin,wuqiangxjtu/zipkin,jfeltesse-mdsol/zipkin,rjbhewei/zipkin,coursera/zipkin,srijs/zipkin,gneokleo/zipkin,Yelp/zipkin,rjbhewei/zipkin,gneokleo/zipkin,yshaojie/zipkin,betable/zipkin,mt0803/zipkin,jfeltesse-mdsol/zipkin,yshaojie/zipkin,prat0318/zipkin,wuqiangxjtu/zipkin,hydro2k/zipkin,mzagar/zipkin,jamescway/zipkin,mzagar/zipkin,hydro2k/zipkin,yshaojie/zipkin,mzagar/zipkin,rocwzp/zipkin,lqjack/zipkin,gneokleo/zipkin,yshaojie/zipkin,rocwzp/zipkin,jamescway/zipkin,lqjack/zipkin,Yelp/zipkin,mzagar/zipkin,jamescway/zipkin,gneokleo/zipkin,srijs/zipkin