--- a/src/java.base/share/classes/java/text/DateFormatSymbols.java	Tue Jan 23 08:26:42 2018 +0100
+++ b/src/java.base/share/classes/java/text/DateFormatSymbols.java	Wed Jan 24 14:07:11 2018 +0530
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1996, 2017, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1996, 2018, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -394,6 +394,12 @@
 
     /**
      * Gets month strings. For example: "January", "February", etc.
+     * An array with either 12 or 13 elements will be returned depending
+     * on whether or not {@link java.util.Calendar#UNDECIMBER Calendar.UNDECIMBER}
+     * is supported. Use
+     * {@link java.util.Calendar#JANUARY Calendar.JANUARY},
+     * {@link java.util.Calendar#FEBRUARY Calendar.FEBRUARY},
+     * etc. to index the result array.
      *
      * <p>If the language requires different forms for formatting and
      * stand-alone usages, this method returns month names in the
@@ -405,10 +411,9 @@
      * Calendar Elements in the Unicode Locale Data Markup Language
      * (LDML) specification</a> for more details.
      *
-     * @return the month strings. Use
-     * {@link java.util.Calendar#JANUARY Calendar.JANUARY},
-     * {@link java.util.Calendar#FEBRUARY Calendar.FEBRUARY},
-     * etc. to index the result array.
+     * @implSpec This method returns 13 elements since
+     * {@link java.util.Calendar#UNDECIMBER Calendar.UNDECIMBER} is supported.
+     * @return the month strings.
      */
     public String[] getMonths() {
         return Arrays.copyOf(months, months.length);
@@ -427,6 +432,12 @@
 
     /**
      * Gets short month strings. For example: "Jan", "Feb", etc.
+     * An array with either 12 or 13 elements will be returned depending
+     * on whether or not {@link java.util.Calendar#UNDECIMBER Calendar.UNDECIMBER}
+     * is supported. Use
+     * {@link java.util.Calendar#JANUARY Calendar.JANUARY},
+     * {@link java.util.Calendar#FEBRUARY Calendar.FEBRUARY},
+     * etc. to index the result array.
      *
      * <p>If the language requires different forms for formatting and
      * stand-alone usages, this method returns short month names in
@@ -438,10 +449,9 @@
      * Calendar Elements in the Unicode Locale Data Markup Language
      * (LDML) specification</a> for more details.
      *
-     * @return the short month strings. Use
-     * {@link java.util.Calendar#JANUARY Calendar.JANUARY},
-     * {@link java.util.Calendar#FEBRUARY Calendar.FEBRUARY},
-     * etc. to index the result array.
+     * @implSpec This method returns 13 elements since
+     * {@link java.util.Calendar#UNDECIMBER Calendar.UNDECIMBER} is supported.
+     * @return the short month strings.
      */
     public String[] getShortMonths() {
         return Arrays.copyOf(shortMonths, shortMonths.length);