Use None instead of empty string as it's slightly smaller/faster
Use None instead of empty string as it's slightly smaller/faster

rikima/spark,milliman/spark,sryza/spark,cloudera/spark,rikima/spark,shaneknapp/spark,byakuinss/spark,szhem/spark,xflin/spark,byakuinss/spark,ddna1021/spark,andrewor14/iolap,vax11780/spark,hvanhovell/spark,guoxiaolongzte/spark,zzcclp/spark,MLnick/spark,map222/spark,minixalpha/spark,aokolnychyi/spark,nilsgrabbert/spark,Aegeaner/spark,kevinyu98/spark,dotunolafunmiloye/spark,wangyum/spark,publicRoman/spark,apache-spark-on-k8s/spark,LantaoJin/spark,saltstar/spark,zhouyejoe/spark,cloudera/spark,holdenk/spark,1haodian/spark,aosagie/spark,andrewor14/spark,wzhfy/spark,darionyaphet/spark,apache/spark,nchammas/spark,setjet/spark,holdenk/spark,rjpower/spark,bdrillard/spark,taroplus/spark,icexelloss/spark,milliman/spark,big-pegasus/spark,witgo/spark,ConeyLiu/spark,rikima/spark,lxsmnv/spark,ibm-research-ireland/sparkoscope,ueshin/apache-spark,ibm-research-ireland/sparkoscope,patrick-nicholson/spark,andrewor14/iolap,facaiy/spark,setjet/spark,mkolod/incubator-spark,publicRoman/spark,caneGuy/spark,lvdongr/spark,aosagie/spark,haowu80s/spark,andrewor14/iolap,aray/spark,JerryLead/spark,BryanCutler/spark,ioana-delaney/spark,xflin/spark,rikima/spark,publicRoman/spark,spark-test/spark,ptkool/spark,huang1900/spark,hhbyyh/spark,WindCanDie/spark,ptkool/spark,dongjoon-hyun/spark,BryanCutler/spark,xflin/spark,MLnick/spark,lxsmnv/spark,xflin/spark,UndeadBaneGitHub/spark,Panos-Bletsos/spark-cost-model-optimizer,liyichao/spark,highfei2011/spark,kiszk/spark,jianran/spark,huang1900/spark,xuanyuanking/spark,vinodkc/spark,HyukjinKwon/spark,szhem/spark,huang1900/spark,alunarbeach/spark,ptkool/spark,chuckchen/spark,michalsenkyr/spark,wangyum/spark,patrick-nicholson/spark,darionyaphet/spark,wangmiao1981/spark,apache-spark-on-k8s/spark,aosagie/spark,bdrillard/spark,someorz/spark,SnappyDataInc/spark,rezasafi/spark,techaddict/spark,zzcclp/spark,lxsmnv/spark,mahak/spark,map222/spark,bOOm-X/spark,jiangxb1987/spark,spark-test/spark,xuanyuanking/spark,esi-mineset/spark,cloudera/spark,zero323/spark,hvanhovell/spark,vinodkc/spark,cloud-fan/spark,gioenn/xSpark,WeichenXu123/spark,michalsenkyr/spark,JerryLead/spark,jkbradley/spark,markhamstra/spark,actuaryzhang/spark,milliman/spark,nchammas/spark,milliman/spark,SnappyDataInc/spark,Panos-Bletsos/spark-cost-model-optimizer,kissmetrics/spark,maropu/spark,dongjoon-hyun/spark,ConeyLiu/spark,jiangxb1987/spark,mdespriee/spark,ericvandenbergfb/spark,tengpeng/spark,cloud-fan/spark,techaddict/spark,xuanyuanking/spark,JoshRosen/spark,narahari92/spark,xflin/spark,ahnqirage/spark,goldmedal/spark,cloudera/spark,ptkool/spark,eyalfa/spark,JoshRosen/spark,kimoonkim/spark,gengliangwang/spark,maropu/spark,ron8hu/spark,dongjoon-hyun/spark,lvdongr/spark,aray/spark,jrshust/spark,metamx/spark,ericvandenbergfb/spark,1haodian/spark,apache/spark,brad-kaiser/spark,zhouyejoe/spark,srowen/spark,cin/spark,xflin/spark,rikima/spark,JerryLead/spark,big-pegasus/spark,bravo-zhang/spark,mdespriee/spark,WindCanDie/spark,joseph-torres/spark,rednaxelafx/apache-spark,ibm-research-ireland/sparkoscope,janewangfb/spark,gengliangwang/spark,zzcclp/spark,akopich/spark,tejasapatil/spark,wangmiao1981/spark,shuangshuangwang/spark,BryanCutler/spark,LantaoJin/spark,zero323/spark,hhbyyh/spark,aosagie/spark,gengliangwang/spark,hhbyyh/spark,Aegeaner/spark,haowu80s/spark,lxsmnv/spark,cin/spark,vinodkc/spark,akopich/spark,bOOm-X/spark,tejasapatil/spark,guoxiaolongzte/spark,map222/spark,joseph-torres/spark,jlopezmalla/spark,skonto/spark,mike0sv/spark,andrewor14/spark,brad-kaiser/spark,highfei2011/spark,saturday-shi/spark,jrshust/spark,dhruve/spark,highfei2011/spark,hvanhovell/spark,zzcclp/spark,HyukjinKwon/spark,sachintyagi22/spark,loneknightpy/spark,shuangshuangwang/spark,wzhfy/spark,actuaryzhang/spark,stanzhai/spark,bravo-zhang/spark,lvdongr/spark,zero323/spark,saltstar/spark,jlopezmalla/spark,metamx/spark,ahnqirage/spark,milliman/spark,JoshRosen/spark,byakuinss/spark,mdespriee/spark,highfei2011/spark,LantaoJin/spark,jianran/spark,BryanCutler/spark,szhem/spark,bdrillard/spark,xuanyuanking/spark,debugger87/spark,Panos-Bletsos/spark-cost-model-optimizer,poffuomo/spark,yanboliang/spark,rjpower/spark,zuotingbing/spark,chuckchen/spark,nlalevee/spark,xuanyuanking/spark,yanboliang/spark,WeichenXu123/spark,zhouyejoe/spark,andrewor14/iolap,jkbradley/spark,witgo/spark,saltstar/spark,ajaysaini725/spark,zuotingbing/spark,LantaoJin/spark,esi-mineset/spark,highfei2011/spark,narahari92/spark,michalsenkyr/spark,icexelloss/spark,chuckchen/spark,kissmetrics/spark,mzl9039/spark,zzcclp/spark,huang1900/spark,kevinyu98/spark,aokolnychyi/spark,wzhfy/spark,esi-mineset/spark,debugger87/spark,shaneknapp/spark,kissmetrics/spark,joseph-torres/spark,jrshust/spark,ConeyLiu/spark,rezasafi/spark,mzl9039/spark,loneknightpy/spark,brad-kaiser/spark,joseph-torres/spark,MLnick/spark,kissmetrics/spark,icexelloss/spark,apache/spark,srowen/spark,UndeadBaneGitHub/spark,mike0sv/spark,icexelloss/spark,map222/spark,publicRoman/spark,apache/spark,minixalpha/spark,cin/spark,WindCanDie/spark,MLnick/spark,LantaoJin/spark,mkolod/incubator-spark,vax11780/spark,alunarbeach/spark,hvanhovell/spark,skonto/spark,ueshin/apache-spark,saturday-shi/spark,poffuomo/spark,markhamstra/spark,panfengfeng/spark,UndeadBaneGitHub/spark,pronix/spark,mike0sv/spark,jiangxb1987/spark,kimoonkim/spark,chuckchen/spark,ioana-delaney/spark,mahak/spark,SnappyDataInc/spark,kimoonkim/spark,chuckchen/spark,pgandhi999/spark,darionyaphet/spark,tejasapatil/spark,ericvandenbergfb/spark,debugger87/spark,ptkool/spark,eyalfa/spark,cin/spark,minixalpha/spark,nilsgrabbert/spark,minixalpha/spark,saturday-shi/spark,dbtsai/spark,poffuomo/spark,jlopezmalla/spark,sryza/spark,joseph-torres/spark,dbtsai/spark,map222/spark,caneGuy/spark,rjpower/spark,yanboliang/spark,dhruve/spark,stanzhai/spark,guoxiaolongzte/spark,taroplus/spark,patrick-nicholson/spark,sryza/spark,guoxiaolongzte/spark,akopich/spark,narahari92/spark,ioana-delaney/spark,bravo-zhang/spark,publicRoman/spark,ddna1021/spark,rednaxelafx/apache-spark,Aegeaner/spark,adrian-ionescu/apache-spark,brad-kaiser/spark,liyichao/spark,eyalfa/spark,adrian-ionescu/apache-spark,spark-test/spark,dhruve/spark,gioenn/xSpark,maropu/spark,mdespriee/spark,mdespriee/spark,ddna1021/spark,ptkool/spark,kiszk/spark,tengpeng/spark,1haodian/spark,ron8hu/spark,facaiy/spark,goldmedal/spark,alunarbeach/spark,rekhajoshm/spark,dbtsai/spark,mzl9039/spark,jiangxb1987/spark,kissmetrics/spark,WeichenXu123/spark,patrick-nicholson/spark,bOOm-X/spark,taroplus/spark,yanboliang/spark,ueshin/apache-spark,metamx/spark,bOOm-X/spark,cin/spark,dbtsai/spark,bravo-zhang/spark,lvdongr/spark,publicRoman/spark,kimoonkim/spark,ConeyLiu/spark,aokolnychyi/spark,vinodkc/spark,apache-spark-on-k8s/spark,tengpeng/spark,gengliangwang/spark,jrshust/spark,ajaysaini725/spark,rezasafi/spark,jlopezmalla/spark,tengpeng/spark,dhruve/spark,haowu80s/spark,poffuomo/spark,rezasafi/spark,sahilTakiar/spark,bravo-zhang/spark,pgandhi999/spark,UndeadBaneGitHub/spark,darionyaphet/spark,setjet/spark,ron8hu/spark,yanboliang/spark,holdenk/spark,akopich/spark,wangmiao1981/spark,sahilTakiar/spark,saturday-shi/spark,gioenn/xSpark,esi-mineset/spark,zhouyejoe/spark,liutang123/spark,sureshthalamati/spark,zhouyejoe/spark,vinodkc/spark,minixalpha/spark,UndeadBaneGitHub/spark,kevinyu98/spark,shubhamchopra/spark,saturday-shi/spark,wzhfy/spark,SHASHANKB/spark,publicRoman/spark,ueshin/apache-spark,tejasapatil/spark,gioenn/xSpark,wangyum/spark,mahak/spark,ahnqirage/spark,mahak/spark,michalsenkyr/spark,ioana-delaney/spark,markhamstra/spark,dongjoon-hyun/spark,dbtsai/spark,skonto/spark,sahilTakiar/spark,srowen/spark,ahnqirage/spark,cloud-fan/spark,stanzhai/spark,gioenn/xSpark,pgandhi999/spark,kimoonkim/spark,lxsmnv/spark,akopich/spark,gengliangwang/spark,holdenk/spark,narahari92/spark,sryza/spark,ericvandenbergfb/spark,patrick-nicholson/spark,liyichao/spark,aray/spark,xuanyuanking/spark,big-pegasus/spark,tejasapatil/spark,WindCanDie/spark,zero323/spark,narahari92/spark,LantaoJin/spark,mike0sv/spark,minixalpha/spark,SHASHANKB/spark,gioenn/xSpark,shubhamchopra/spark,huang1900/spark,spark-test/spark,kissmetrics/spark,ajaysaini725/spark,dhruve/spark,JerryLead/spark,ddna1021/spark,1haodian/spark,vinodkc/spark,wangmiao1981/spark,SHASHANKB/spark,aosagie/spark,poffuomo/spark,caneGuy/spark,nilsgrabbert/spark,metamx/spark,andrewor14/spark,rikima/spark,actuaryzhang/spark,setjet/spark,jlopezmalla/spark,kiszk/spark,rjpower/spark,rednaxelafx/apache-spark,HyukjinKwon/spark,nlalevee/spark,apache-spark-on-k8s/spark,kiszk/spark,someorz/spark,nilsgrabbert/spark,shubhamchopra/spark,kimoonkim/spark,adrian-ionescu/apache-spark,guoxiaolongzte/spark,michalsenkyr/spark,someorz/spark,minixalpha/spark,huang1900/spark,UndeadBaneGitHub/spark,mahak/spark,janewangfb/spark,bOOm-X/spark,brad-kaiser/spark,Aegeaner/spark,srowen/spark,nlalevee/spark,pronix/spark,pronix/spark,kiszk/spark,bdrillard/spark,ajaysaini725/spark,facaiy/spark,alunarbeach/spark,bdrillard/spark,jkbradley/spark,byakuinss/spark,andrewor14/iolap,JoshRosen/spark,sureshthalamati/spark,saltstar/spark,MLnick/spark,eyalfa/spark,shuangshuangwang/spark,rezasafi/spark,dotunolafunmiloye/spark,nlalevee/spark,nchammas/spark,wangyum/spark,WeichenXu123/spark,lvdongr/spark,dhruve/spark,sureshthalamati/spark,zuotingbing/spark,szhem/spark,SnappyDataInc/spark,pronix/spark,aray/spark,joseph-torres/spark,jianran/spark,matthewfranglen/spark,zero323/spark,ajaysaini725/spark,SnappyDataInc/spark,alunarbeach/spark,darionyaphet/spark,pronix/spark,Panos-Bletsos/spark-cost-model-optimizer,janewangfb/spark,sureshthalamati/spark,zuotingbing/spark,dhruve/spark,michalsenkyr/spark,Panos-Bletsos/spark-cost-model-optimizer,ueshin/apache-spark,setjet/spark,ron8hu/spark,Aegeaner/spark,actuaryzhang/spark,skonto/spark,panfengfeng/spark,hvanhovell/spark,brad-kaiser/spark,zzcclp/spark,holdenk/spark,vax11780/spark,guoxiaolongzte/spark,ron8hu/spark,hhbyyh/spark,aokolnychyi/spark,nilsgrabbert/spark,ron8hu/spark,poffuomo/spark,MLnick/spark,xflin/spark,rekhajoshm/spark,haowu80s/spark,andrewor14/spark,ibm-research-ireland/sparkoscope,panfengfeng/spark,szhem/spark,poffuomo/spark,JoshRosen/spark,hhbyyh/spark,yanboliang/spark,andrewor14/iolap,WindCanDie/spark,andrewor14/spark,kiszk/spark,Aegeaner/spark,srowen/spark,aokolnychyi/spark,ioana-delaney/spark,jrshust/spark,shuangshuangwang/spark,zhouyejoe/spark,panfengfeng/spark,jlopezmalla/spark,highfei2011/spark,someorz/spark,shubhamchopra/spark,adrian-ionescu/apache-spark,mkolod/incubator-spark,sureshthalamati/spark,wzhfy/spark,tengpeng/spark,sachintyagi22/spark,rekhajoshm/spark,mzl9039/spark,JerryLead/spark,szhem/spark,esi-mineset/spark,wangyum/spark,WeichenXu123/spark,shaneknapp/spark,liutang123/spark,techaddict/spark,xuanyuanking/spark,markhamstra/spark,rekhajoshm/spark,ron8hu/spark,maropu/spark,apache/spark,shuangshuangwang/spark,tejasapatil/spark,loneknightpy/spark,aosagie/spark,aray/spark,witgo/spark,nchammas/spark,WeichenXu123/spark,jianran/spark,markhamstra/spark,metamx/spark,cloud-fan/spark,mike0sv/spark,hvanhovell/spark,jlopezmalla/spark,zuotingbing/spark,aosagie/spark,panfengfeng/spark,dbtsai/spark,actuaryzhang/spark,Aegeaner/spark,aray/spark,goldmedal/spark,sachintyagi22/spark,ConeyLiu/spark,stanzhai/spark,sachintyagi22/spark,sachintyagi22/spark,BryanCutler/spark,ptkool/spark,ibm-research-ireland/sparkoscope,ConeyLiu/spark,darionyaphet/spark,aokolnychyi/spark,rezasafi/spark,ibm-research-ireland/sparkoscope,markhamstra/spark,pgandhi999/spark,andrewor14/iolap,metamx/spark,1haodian/spark,JerryLead/spark,liutang123/spark,apache/spark,gioenn/xSpark,JoshRosen/spark,stanzhai/spark,MLnick/spark,saltstar/spark,darionyaphet/spark,akopich/spark,wangmiao1981/spark,goldmedal/spark,narahari92/spark,icexelloss/spark,mzl9039/spark,caneGuy/spark,shaneknapp/spark,byakuinss/spark,tejasapatil/spark,wangyum/spark,ahnqirage/spark,nlalevee/spark,rednaxelafx/apache-spark,saturday-shi/spark,bdrillard/spark,nlalevee/spark,nilsgrabbert/spark,mdespriee/spark,big-pegasus/spark,cloud-fan/spark,patrick-nicholson/spark,saltstar/spark,jianran/spark,cloudera/spark,skonto/spark,janewangfb/spark,patrick-nicholson/spark,ueshin/apache-spark,actuaryzhang/spark,narahari92/spark,spark-test/spark,kimoonkim/spark,facaiy/spark,facaiy/spark,sryza/spark,mdespriee/spark,SHASHANKB/spark,maropu/spark,ajaysaini725/spark,spark-test/spark,sahilTakiar/spark,wangyum/spark,nchammas/spark,ericvandenbergfb/spark,ueshin/apache-spark,liutang123/spark,rjpower/spark,nchammas/spark,dotunolafunmiloye/spark,big-pegasus/spark,mzl9039/spark,dotunolafunmiloye/spark,ddna1021/spark,big-pegasus/spark,techaddict/spark,joseph-torres/spark,brad-kaiser/spark,taroplus/spark,liyichao/spark,caneGuy/spark,wzhfy/spark,shaneknapp/spark,rednaxelafx/apache-spark,WindCanDie/spark,alunarbeach/spark,metamx/spark,adrian-ionescu/apache-spark,HyukjinKwon/spark,bravo-zhang/spark,liutang123/spark,gengliangwang/spark,goldmedal/spark,maropu/spark,nlalevee/spark,panfengfeng/spark,apache/spark,andrewor14/spark,zero323/spark,WeichenXu123/spark,setjet/spark,hhbyyh/spark,bOOm-X/spark,jrshust/spark,esi-mineset/spark,chuckchen/spark,markhamstra/spark,debugger87/spark,liutang123/spark,ibm-research-ireland/sparkoscope,facaiy/spark,tengpeng/spark,Panos-Bletsos/spark-cost-model-optimizer,big-pegasus/spark,holdenk/spark,BryanCutler/spark,aokolnychyi/spark,srowen/spark,szhem/spark,lxsmnv/spark,skonto/spark,ddna1021/spark,highfei2011/spark,wangmiao1981/spark,jianran/spark,techaddict/spark,kevinyu98/spark,jkbradley/spark,sahilTakiar/spark,ahnqirage/spark,maropu/spark,HyukjinKwon/spark,Panos-Bletsos/spark-cost-model-optimizer,eyalfa/spark,jianran/spark,pgandhi999/spark,actuaryzhang/spark,someorz/spark,jkbradley/spark,debugger87/spark,SHASHANKB/spark,liyichao/spark,hvanhovell/spark,alunarbeach/spark,srowen/spark,hhbyyh/spark,kiszk/spark,gengliangwang/spark,SnappyDataInc/spark,kevinyu98/spark,liutang123/spark,shuangshuangwang/spark,stanzhai/spark,rekhajoshm/spark,milliman/spark,mahak/spark,JerryLead/spark,mzl9039/spark,panfengfeng/spark,dongjoon-hyun/spark,taroplus/spark,rednaxelafx/apache-spark,cin/spark,SHASHANKB/spark,witgo/spark,WindCanDie/spark,rednaxelafx/apache-spark,ConeyLiu/spark,1haodian/spark,rezasafi/spark,witgo/spark,caneGuy/spark,SHASHANKB/spark,ahnqirage/spark,saturday-shi/spark,yanboliang/spark,pgandhi999/spark,1haodian/spark,apache-spark-on-k8s/spark,dbtsai/spark,sureshthalamati/spark,mahak/spark,mike0sv/spark,guoxiaolongzte/spark,icexelloss/spark,bdrillard/spark,jkbradley/spark,UndeadBaneGitHub/spark,debugger87/spark,aray/spark,esi-mineset/spark,dongjoon-hyun/spark,nchammas/spark,ddna1021/spark,bOOm-X/spark,cloud-fan/spark,ioana-delaney/spark,saltstar/spark,loneknightpy/spark,techaddict/spark,vinodkc/spark,shubhamchopra/spark,dongjoon-hyun/spark,LantaoJin/spark,haowu80s/spark,ericvandenbergfb/spark,skonto/spark,lxsmnv/spark,vax11780/spark,stanzhai/spark,pgandhi999/spark,mkolod/incubator-spark,janewangfb/spark,ioana-delaney/spark,ericvandenbergfb/spark,akopich/spark,janewangfb/spark,someorz/spark,jiangxb1987/spark,goldmedal/spark,icexelloss/spark,cloud-fan/spark,jiangxb1987/spark,facaiy/spark,shaneknapp/spark,SnappyDataInc/spark,bravo-zhang/spark,adrian-ionescu/apache-spark,caneGuy/spark,holdenk/spark,vax11780/spark,zuotingbing/spark,goldmedal/spark,spark-test/spark,byakuinss/spark,rikima/spark,zzcclp/spark,michalsenkyr/spark,kissmetrics/spark,shuangshuangwang/spark,loneknightpy/spark,byakuinss/spark,jiangxb1987/spark,witgo/spark,loneknightpy/spark,zhouyejoe/spark,techaddict/spark,apache-spark-on-k8s/spark,lvdongr/spark,taroplus/spark,JoshRosen/spark,ajaysaini725/spark,kevinyu98/spark,liyichao/spark,rekhajoshm/spark,sachintyagi22/spark,mike0sv/spark,sachintyagi22/spark,kevinyu98/spark,taroplus/spark,nilsgrabbert/spark,someorz/spark,haowu80s/spark,wzhfy/spark,loneknightpy/spark,mkolod/incubator-spark,setjet/spark,HyukjinKwon/spark,eyalfa/spark,jkbradley/spark,milliman/spark,debugger87/spark,map222/spark,HyukjinKwon/spark,huang1900/spark,chuckchen/spark,shubhamchopra/spark,zero323/spark,sahilTakiar/spark,liyichao/spark,eyalfa/spark,BryanCutler/spark,adrian-ionescu/apache-spark,sahilTakiar/spark,pronix/spark,cin/spark,rekhajoshm/spark,witgo/spark,zuotingbing/spark,shaneknapp/spark,jrshust/spark,sureshthalamati/spark,tengpeng/spark,janewangfb/spark,shubhamchopra/spark,map222/spark,wangmiao1981/spark,lvdongr/spark,andrewor14/spark,apache-spark-on-k8s/spark