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

@@ -1,7 +1,7 @@
 /*
- * 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
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.  Oracle designates this

@@ -392,10 +392,13 @@
         cachedHashCode = 0;
     }
 
     /**
      * Gets month strings. For example: "January", "February", etc.
+     * An array with either 12 or 13 elements will be returned depending
+     * on whether or {@link java.util.Calendar#UNDECIMBER Calendar.UNDECIMBER}
+     * is supported.
      *
      * <p>If the language requires different forms for formatting and
      * stand-alone usages, this method returns month names in the
      * formatting form. For example, the preferred month name for
      * January in the Czech language is <em>ledna</em> in the

@@ -403,10 +406,12 @@
      * form. This method returns {@code "ledna"} in this case. Refer
      * to the <a href="http://unicode.org/reports/tr35/#Calendar_Elements">
      * Calendar Elements in the Unicode Locale Data Markup Language
      * (LDML) specification</a> for more details.
      *
+     * @implSpec This method returns 13 elements since 
+     * {@link java.util.Calendar#UNDECIMBER Calendar.UNDECIMBER} is supported.
      * @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.
      */

@@ -425,10 +430,13 @@
         cachedHashCode = 0;
     }
 
     /**
      * Gets short month strings. For example: "Jan", "Feb", etc.
+     * An array with either 12 or 13 elements will be returned depending
+     * on whether or {@link java.util.Calendar#UNDECIMBER Calendar.UNDECIMBER}
+     * is supported.
      *
      * <p>If the language requires different forms for formatting and
      * stand-alone usages, this method returns short month names in
      * the formatting form. For example, the preferred abbreviation
      * for January in the Catalan language is <em>de gen.</em> in the

@@ -436,10 +444,12 @@
      * form. This method returns {@code "de gen."} in this case. Refer
      * to the <a href="http://unicode.org/reports/tr35/#Calendar_Elements">
      * Calendar Elements in the Unicode Locale Data Markup Language
      * (LDML) specification</a> for more details.
      *
+     * @implSpec This method returns 13 elements since 
+     * {@link java.util.Calendar#UNDECIMBER Calendar.UNDECIMBER} is supported.
      * @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.
      */