Fix

Author: maropu

sql/catalyst/src/main/java/org/apache/spark/sql/catalyst/expressions/ExpressionDescription.java

@@ -103,6 +103,12 @@
     String arguments() default "";
     String examples() default "";
     String note() default "";
+    /**
+     * Valid group names are almost the same with one defined as `groupname` in
+     * `sql/functions.scala`. But, `collection_funcs` is split into fine-grained three groups:
+     * `array_funcs`, `map_funcs`, and `json_funcs`. See `ExpressionInfo` for the
+     * detailed group names.
+     */
     String group() default "";
     String since() default "";
     String deprecated() default "";

sql/catalyst/src/main/java/org/apache/spark/sql/catalyst/expressions/ExpressionInfo.java

@@ -39,9 +39,6 @@ public class ExpressionInfo {
     private String since;
     private String deprecated;
 
-    // The groups below are almost the same with ones defined in `sql/functions.sql`.
-    // But, `collection_funcs` is split into fine-grained three groups: `array_funcs`, `map_funcs`,
-    // and `json_funcs`.
     private static final Set<String> validGroups =
         new HashSet<>(Arrays.asList("agg_funcs", "array_funcs", "datetime_funcs",
             "json_funcs", "map_funcs", "window_funcs"));