SPARK-2148 Add link to requirements for custom equals() and hashcode() methods
SPARK-2148 Add link to requirements for custom equals() and hashcode() methods

https://issues.apache.org/jira/browse/SPARK-2148

Author: Andrew Ash <andrew@andrewash.com>

Closes #1092 from ash211/SPARK-2148 and squashes the following commits:

93513df [Andrew Ash] SPARK-2148 Add link to requirements for custom equals() and hashcode() methods

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