8319628: DateFormat does not mention IllegalArgumentException for inv…

…alid style args

Reviewed-by: naoto

src/java.base/share/classes/java/text/DateFormat.java

@@ -61,10 +61,12 @@
  * normalization.  The date is represented as a {@code Date} object or
  * as the milliseconds since January 1, 1970, 00:00:00 GMT.
  *
- * <p>{@code DateFormat} provides many class methods for obtaining default date/time
+ * <p>{@code DateFormat} provides static factory methods for obtaining default date/time
  * formatters based on the default or a given locale and a number of formatting
- * styles. The formatting styles include {@link #FULL}, {@link #LONG}, {@link #MEDIUM}, and {@link #SHORT}. More
- * detail and examples of using these styles are provided in the method
+ * styles. The formatting styles include {@link #FULL}, {@link #LONG}, {@link #MEDIUM}, and {@link #SHORT}.
+ * For any of the factory methods with the parameter <i>style</i>, an {@code
+ * IllegalArgumentException} will be thrown if <i>style</i> is not equal to any
+ * of the defined formatting styles. More detail and examples of using these styles are provided in the method
  * descriptions.
  *
  * <p>{@code DateFormat} helps you to format and parse dates for any locale.
@@ -162,7 +164,7 @@
  * {@code null}, but any subsequent operations on the same instance may throw
  * {@code NullPointerException}.</li>
  * <li>The {@link #getCalendar()}, {@link #getNumberFormat()} and
- * {@link getTimeZone()} methods may return {@code null}, if the respective
+ * {@link #getTimeZone()} methods may return {@code null}, if the respective
  * values of this instance is set to {@code null} through the corresponding
  * setter methods. For Example: {@link #getTimeZone()} may return {@code null},
  * if the {@code TimeZone} value of this instance is set as