[SPARK-20359][SQL] Avoid unnecessary execution in EliminateOuterJoin optimization that can lead to NPE#17660

koertkuipers wants to merge 3 commits intoapache:masterapache/spark:masterfrom

tresata-opensource:feat-catch-npe-in-eliminate-outer-jointresata-opensource/spark:feat-catch-npe-in-eliminate-outer-joinCopy head branch name to clipboard