From 90477b40a4b92c357184cc182f546ce742b1ffa1 Mon Sep 17 00:00:00 2001
From: Phillip Webb <pwebb@pivotal.io>
Date: Mon, 1 May 2017 21:26:16 -0700
Subject: [PATCH] Defer Charset.availableCharsets() call

Change the `StringHttpMessageConverter` to defer calling
Charset.availableCharsets() until absolutely necessary to help improve
startup times.

Issue: SPR-15502
---
 .../http/converter/StringHttpMessageConverter.java         | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/spring-web/src/main/java/org/springframework/http/converter/StringHttpMessageConverter.java b/spring-web/src/main/java/org/springframework/http/converter/StringHttpMessageConverter.java
index f3c7c5f978..33e915611d 100644
--- a/spring-web/src/main/java/org/springframework/http/converter/StringHttpMessageConverter.java
+++ b/spring-web/src/main/java/org/springframework/http/converter/StringHttpMessageConverter.java
@@ -43,7 +43,7 @@ public class StringHttpMessageConverter extends AbstractHttpMessageConverter<Str
 	public static final Charset DEFAULT_CHARSET = StandardCharsets.ISO_8859_1;
 
 
-	private final List<Charset> availableCharsets;
+	private volatile List<Charset> availableCharsets;
 
 	private boolean writeAcceptCharset = true;
 
@@ -62,7 +62,6 @@ public class StringHttpMessageConverter extends AbstractHttpMessageConverter<Str
 	 */
 	public StringHttpMessageConverter(Charset defaultCharset) {
 		super(defaultCharset, MediaType.TEXT_PLAIN, MediaType.ALL);
-		this.availableCharsets = new ArrayList<>(Charset.availableCharsets().values());
 	}
 
 
@@ -109,6 +108,10 @@ public class StringHttpMessageConverter extends AbstractHttpMessageConverter<Str
 	 * @return the list of accepted charsets
 	 */
 	protected List<Charset> getAcceptedCharsets() {
+		if (this.availableCharsets == null) {
+			this.availableCharsets = new ArrayList<>(
+					Charset.availableCharsets().values());
+		}
 		return this.availableCharsets;
 	}