From b9e190e313cd49c895f92626a37e170b42d827e8 Mon Sep 17 00:00:00 2001
From: Brian Clozel <brian.clozel@broadcom.com>
Date: Mon, 16 Feb 2026 18:48:26 +0100
Subject: [PATCH] Fix HttpMessageConverters configurers support

This commit fixes the `configureMessageConverters` and
`configureMessageConvertersList` behavior.

`configureMessageConverters` was not executing consumers in their order
of registration (but in the reverse order).
`configureMessageConvertersList` was not executing multiple consumers
and was instead executing the first consumer multiple times.

This commit fixes both issues.

Fixes gh-36332
---
 .../DefaultHttpMessageConverters.java         |  4 +-
 .../DefaultHttpMessageConvertersTests.java    | 40 ++++++++++++++-----
 2 files changed, 31 insertions(+), 13 deletions(-)

diff --git a/spring-web/src/main/java/org/springframework/http/converter/DefaultHttpMessageConverters.java b/spring-web/src/main/java/org/springframework/http/converter/DefaultHttpMessageConverters.java
index 0bd936c977c..0c50bb36955 100644
--- a/spring-web/src/main/java/org/springframework/http/converter/DefaultHttpMessageConverters.java
+++ b/spring-web/src/main/java/org/springframework/http/converter/DefaultHttpMessageConverters.java
@@ -225,12 +225,12 @@ class DefaultHttpMessageConverters implements HttpMessageConverters {
 		}
 
 		void addMessageConverterConfigurer(Consumer<HttpMessageConverter<?>> configurer) {
-			this.configurer = (this.configurer != null) ? configurer.andThen(this.configurer) : configurer;
+			this.configurer = (this.configurer != null) ? this.configurer.andThen(configurer) : configurer;
 		}
 
 		void addMessageConvertersListConfigurer(Consumer<List<HttpMessageConverter<?>>> configurer) {
 			this.convertersListConfigurer = (this.convertersListConfigurer != null) ?
-					this.convertersListConfigurer.andThen(this.convertersListConfigurer) : configurer;
+					this.convertersListConfigurer.andThen(configurer) : configurer;
 		}
 
 		List<HttpMessageConverter<?>> getBaseConverters() {
diff --git a/spring-web/src/test/java/org/springframework/http/converter/DefaultHttpMessageConvertersTests.java b/spring-web/src/test/java/org/springframework/http/converter/DefaultHttpMessageConvertersTests.java
index a9196ce44c5..dcef8369b35 100644
--- a/spring-web/src/test/java/org/springframework/http/converter/DefaultHttpMessageConvertersTests.java
+++ b/spring-web/src/test/java/org/springframework/http/converter/DefaultHttpMessageConvertersTests.java
@@ -210,22 +210,31 @@ class DefaultHttpMessageConvertersTests {
 					.addCustomConverter(customConverter)
 					.configureMessageConverters(converter -> {
 						if (converter instanceof CustomHttpMessageConverter custom) {
-							custom.processed = true;
+							assertThat(custom.processCount).isZero();
+							custom.processCount++;
+						}
+					})
+					.configureMessageConverters(converter -> {
+						if (converter instanceof CustomHttpMessageConverter custom) {
+							assertThat(custom.processCount).isEqualTo(1);
+							custom.processCount++;
 						}
 					}).build();
 
-			assertThat(customConverter.processed).isTrue();
+			assertThat(customConverter.processCount).isEqualTo(2);
 		}
 
 		@Test
 		void shouldAppendCustomConverterToList() {
-			var customConverter = new CustomHttpMessageConverter();
+			var firstCustom = new CustomHttpMessageConverter();
+			var secondCustom = new CustomHttpMessageConverter();
 			var messageConverters = HttpMessageConverters.forClient()
 					.registerDefaults()
-					.configureMessageConvertersList(converters -> converters.add(customConverter))
+					.configureMessageConvertersList(converters -> converters.add(firstCustom))
+					.configureMessageConvertersList(converters -> converters.add(secondCustom))
 					.build();
 
-			assertThat(messageConverters).last().isInstanceOf(CustomHttpMessageConverter.class);
+			assertThat(messageConverters).containsSequence(firstCustom, secondCustom);
 		}
 
 	}
@@ -336,22 +345,31 @@ class DefaultHttpMessageConvertersTests {
 					.addCustomConverter(customConverter)
 					.configureMessageConverters(converter -> {
 						if (converter instanceof CustomHttpMessageConverter custom) {
-							custom.processed = true;
+							assertThat(custom.processCount).isZero();
+							custom.processCount++;
+						}
+					})
+					.configureMessageConverters(converter -> {
+						if (converter instanceof CustomHttpMessageConverter custom) {
+							assertThat(custom.processCount).isEqualTo(1);
+							custom.processCount++;
 						}
 					}).build();
 
-			assertThat(customConverter.processed).isTrue();
+			assertThat(customConverter.processCount).isEqualTo(2);
 		}
 
 		@Test
 		void shouldAppendCustomConverterToList() {
-			var customConverter = new CustomHttpMessageConverter();
+			var firstCustom = new CustomHttpMessageConverter();
+			var secondCustom = new CustomHttpMessageConverter();
 			var messageConverters = HttpMessageConverters.forServer()
 					.registerDefaults()
-					.configureMessageConvertersList(converters -> converters.add(customConverter))
+					.configureMessageConvertersList(converters -> converters.add(firstCustom))
+					.configureMessageConvertersList(converters -> converters.add(secondCustom))
 					.build();
 
-			assertThat(messageConverters).last().isInstanceOf(CustomHttpMessageConverter.class);
+			assertThat(messageConverters).containsSequence(firstCustom, secondCustom);
 		}
 	}
 
@@ -365,7 +383,7 @@ class DefaultHttpMessageConvertersTests {
 
 	static class CustomHttpMessageConverter extends AbstractHttpMessageConverter<Object> {
 
-		boolean processed = false;
+		int processCount;
 
 		@Override
 		protected boolean supports(Class<?> clazz) {