Address comments.

Author: ueshin

docs/sql-migration-guide-upgrade.md

@@ -17,7 +17,7 @@ displayTitle: Spark SQL Upgrading Guide
 
   - The `ADD JAR` command previously returned a result set with the single value 0. It now returns an empty result set.
 
-  - In Spark version 2.4 and earlier, the `SET` command works without any warnings even if the specified key is for `SparkConf` entries and it has no effect because the command does not update `SparkConf`, but the behavior might confuse users. Since 3.0, the command fails if the key is for `SparkConf` as same as for static sql config keys. You can disable such a check by setting `spark.sql.execution.setCommandRejectsSparkConfs` to `false`.
+  - In Spark version 2.4 and earlier, the `SET` command works without any warnings even if the specified key is for `SparkConf` entries and it has no effect because the command does not update `SparkConf`, but the behavior might confuse users. Since 3.0, the command fails if a non-SQL or static SQL config key is used. You can disable such a check by setting `spark.sql.execution.setCommandRejectsSparkConfs` to `false`.
 
 ## Upgrading From Spark SQL 2.3 to 2.4
 

sql/core/src/main/scala/org/apache/spark/sql/RuntimeConfig.scala

@@ -156,7 +156,7 @@ class RuntimeConfig private[sql](sqlConf: SQLConf = new SQLConf) {
     }
     if (sqlConf.setCommandRejectsSparkConfs &&
         ConfigEntry.findEntry(key) != null && !SQLConf.sqlConfEntries.containsKey(key)) {
-      throw new AnalysisException(s"Cannot modify the value of a spark config: $key")
+      throw new AnalysisException(s"Cannot modify the value of a Spark config: $key")
     }
   }
 }

sql/core/src/test/scala/org/apache/spark/sql/RuntimeConfigSuite.scala

@@ -75,6 +75,6 @@ class RuntimeConfigSuite extends SparkFunSuite {
     val ex = intercept[AnalysisException] {
       conf.set("spark.task.cpus", 4)
     }
-    assert(ex.getMessage.contains("spark config"))
+    assert(ex.getMessage.contains("Spark config"))
   }
 }

sql/core/src/test/scala/org/apache/spark/sql/execution/command/DDLSuite.scala

@@ -2720,6 +2720,6 @@ abstract class DDLSuite extends QueryTest with SQLTestUtils {
     val ex = intercept[AnalysisException] {
       sql("SET spark.task.cpus = 4")
     }
-    assert(ex.getMessage.contains("spark config"))
+    assert(ex.getMessage.contains("Spark config"))
   }
 }