From 075b3e1a409f685ce412dbea2458990f2dbc699e Mon Sep 17 00:00:00 2001
From: Gary Gregory <garydgregory@gmail.com>
Date: Thu, 10 Aug 2023 14:13:19 -0400
Subject: [PATCH] Add invariant check in
 FastDateParser.appendDisplayNames(Calendar, Locale, int, StringBuilder)

---
 src/main/java/org/apache/commons/lang3/time/FastDateParser.java | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/main/java/org/apache/commons/lang3/time/FastDateParser.java b/src/main/java/org/apache/commons/lang3/time/FastDateParser.java
index 6851a4dc4..a043a1706 100644
--- a/src/main/java/org/apache/commons/lang3/time/FastDateParser.java
+++ b/src/main/java/org/apache/commons/lang3/time/FastDateParser.java
@@ -488,6 +488,7 @@ public class FastDateParser implements DateParser, Serializable {
      */
     private static Map<String, Integer> appendDisplayNames(final Calendar calendar, final Locale locale, final int field,
             final StringBuilder regex) {
+        Objects.requireNonNull(calendar, "calendar");
         final Map<String, Integer> values = new HashMap<>();
         final Locale actualLocale = LocaleUtils.toLocale(locale);
         final Map<String, Integer> displayNames = calendar.getDisplayNames(field, Calendar.ALL_STYLES, actualLocale);