Make sure that Arguments and Examples have a correct format

Author: tanelk

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

@@ -105,8 +105,9 @@ public ExpressionInfo(
             String deprecated) {
         assert name != null;
         assert arguments != null;
+        assert arguments.isEmpty() || arguments.startsWith("\n    Arguments:\n");
         assert examples != null;
-        assert examples.isEmpty() || examples.contains("    Examples:");
+        assert examples.isEmpty() || examples.startsWith("\n    Examples:\n");
         assert note != null;
         assert group != null;
         assert since != null;

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/datetimeExpressions.scala

@@ -1565,13 +1565,13 @@ trait TruncInstant extends BinaryExpression with ImplicitCastInputTypes {
     _FUNC_(date, fmt) - Returns `date` with the time portion of the day truncated to the unit specified by the format model `fmt`.
   """,
   arguments = """
-     Arguments:
-       * date - date value or valid date string
-       * fmt - the format representing the unit to be truncated to
-           - "YEAR", "YYYY", "YY" - truncate to the first date of the year that the `date` falls in
-           - "QUARTER" - truncate to the first date of the quarter that the `date` falls in
-           - "MONTH", "MM", "MON" - truncate to the first date of the month that the `date` falls in
-           - "WEEK" - truncate to the Monday of the week that the `date` falls in
+    Arguments:
+      * date - date value or valid date string
+      * fmt - the format representing the unit to be truncated to
+          - "YEAR", "YYYY", "YY" - truncate to the first date of the year that the `date` falls in
+          - "QUARTER" - truncate to the first date of the quarter that the `date` falls in
+          - "MONTH", "MM", "MON" - truncate to the first date of the month that the `date` falls in
+          - "WEEK" - truncate to the Monday of the week that the `date` falls in
   """,
   examples = """
     Examples:
@@ -1619,19 +1619,19 @@ case class TruncDate(date: Expression, format: Expression)
     _FUNC_(fmt, ts) - Returns timestamp `ts` truncated to the unit specified by the format model `fmt`.
   """,
   arguments = """
-     Arguments:
-       * fmt - the format representing the unit to be truncated to
-           - "YEAR", "YYYY", "YY" - truncate to the first date of the year that the `ts` falls in, the time part will be zero out
-           - "QUARTER" - truncate to the first date of the quarter that the `ts` falls in, the time part will be zero out
-           - "MONTH", "MM", "MON" - truncate to the first date of the month that the `ts` falls in, the time part will be zero out
-           - "WEEK" - truncate to the Monday of the week that the `ts` falls in, the time part will be zero out
-           - "DAY", "DD" - zero out the time part
-           - "HOUR" - zero out the minute and second with fraction part
-           - "MINUTE"- zero out the second with fraction part
-           - "SECOND" -  zero out the second fraction part
-           - "MILLISECOND" - zero out the microseconds
-           - "MICROSECOND" - everything remains
-       * ts - datetime value or valid timestamp string
+    Arguments:
+      * fmt - the format representing the unit to be truncated to
+          - "YEAR", "YYYY", "YY" - truncate to the first date of the year that the `ts` falls in, the time part will be zero out
+          - "QUARTER" - truncate to the first date of the quarter that the `ts` falls in, the time part will be zero out
+          - "MONTH", "MM", "MON" - truncate to the first date of the month that the `ts` falls in, the time part will be zero out
+          - "WEEK" - truncate to the Monday of the week that the `ts` falls in, the time part will be zero out
+          - "DAY", "DD" - zero out the time part
+          - "HOUR" - zero out the minute and second with fraction part
+          - "MINUTE"- zero out the second with fraction part
+          - "SECOND" -  zero out the second fraction part
+          - "MILLISECOND" - zero out the microseconds
+          - "MICROSECOND" - everything remains
+      * ts - datetime value or valid timestamp string
   """,
   examples = """
     Examples:

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/misc.scala

@@ -208,11 +208,11 @@ case class SparkVersion() extends LeafExpression with CodegenFallback {
 @ExpressionDescription(
   usage = """_FUNC_(expr) - Return DDL-formatted type string for the data type of the input.""",
   examples = """
-      Examples:
-      > SELECT _FUNC_(1);
-       int
-      > SELECT _FUNC_(array(1));
-       array<int>
+    Examples:
+     > SELECT _FUNC_(1);
+      int
+     > SELECT _FUNC_(array(1));
+      array<int>
   """,
   since = "3.0.0")
 case class TypeOf(child: Expression) extends UnaryExpression {