Add the some error infomation if using spark-sql in yarn-cluster mode

core/src/main/scala/org/apache/spark/deploy/SparkSubmit.scala

@@ -142,8 +142,8 @@ object SparkSubmit {
         printErrorAndExit("Cluster deploy mode is currently not supported for python applications.")
       case (_, CLUSTER) if isShell(args.primaryResource) =>
         printErrorAndExit("Cluster deploy mode is not applicable to Spark shells.")
-      case (_, CLUSTER) if isSql(args.mainClass) =>
-        printErrorAndExit("Cluster deploy mode is not applicable to Spark SQLs.")
+      case (_, CLUSTER) if isSqlShell(args.mainClass) =>
+        printErrorAndExit("Cluster deploy mode is not applicable to Spark Sql shells.")
       case _ =>
     }
 
@@ -393,7 +393,7 @@ object SparkSubmit {
   /**
    * Return whether the given main class represents a sql shell.
    */
-  private[spark] def isSql(mainClass: String): Boolean = {
+  private[spark] def isSqlShell(mainClass: String): Boolean = {
     mainClass == "org.apache.spark.sql.hive.thriftserver.SparkSQLCLIDriver"
   }