Pregel example type fix
Pregel example type fix

Pregel example to express single source shortest path from https://spark.apache.org/docs/latest/graphx-programming-guide.html#pregel-api does not work due to incorrect type. The reason is that `GraphGenerators.logNormalGraph` returns the graph with `Long` vertices. Fixing `val graph: Graph[Int, Double]` to `val graph: Graph[Long, Double]`.

Author: Alexander Ulanov <nashb@yandex.ru>

Closes #7695 from avulanov/SPARK-9380-pregel-doc and squashes the following commits:

c269429 [Alexander Ulanov] Pregel example type fix

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