From 0fe7d78732b54de599aa6c974a105653cb058be4 Mon Sep 17 00:00:00 2001
From: Phillip Webb <phil.webb@broadcom.com>
Date: Mon, 11 Dec 2023 16:41:14 -0800
Subject: [PATCH] Restore support for custom bind converters in collections

Update the `beansConverterService` introduced in commit f4e05c91c74e
so that it can also handle collection based conversions.

Fixes gh-38734
---
 .../properties/ConversionServiceDeducer.java  |  2 +
 .../ConfigurationPropertiesTests.java         | 40 +++++++++++++++++++
 2 files changed, 42 insertions(+)

diff --git a/spring-boot-project/spring-boot/src/main/java/org/springframework/boot/context/properties/ConversionServiceDeducer.java b/spring-boot-project/spring-boot/src/main/java/org/springframework/boot/context/properties/ConversionServiceDeducer.java
index 775680c794ae..a80535000f6f 100644
--- a/spring-boot-project/spring-boot/src/main/java/org/springframework/boot/context/properties/ConversionServiceDeducer.java
+++ b/spring-boot-project/spring-boot/src/main/java/org/springframework/boot/context/properties/ConversionServiceDeducer.java
@@ -29,6 +29,7 @@
 import org.springframework.core.convert.ConversionService;
 import org.springframework.core.convert.converter.Converter;
 import org.springframework.core.convert.converter.GenericConverter;
+import org.springframework.core.convert.support.DefaultConversionService;
 import org.springframework.format.Formatter;
 import org.springframework.format.FormatterRegistry;
 import org.springframework.format.support.FormattingConversionService;
@@ -63,6 +64,7 @@ private List<ConversionService> getConversionServices(ConfigurableApplicationCon
 		ConverterBeans converterBeans = new ConverterBeans(applicationContext);
 		if (!converterBeans.isEmpty()) {
 			FormattingConversionService beansConverterService = new FormattingConversionService();
+			DefaultConversionService.addCollectionConverters(beansConverterService);
 			converterBeans.addTo(beansConverterService);
 			conversionServices.add(beansConverterService);
 		}
diff --git a/spring-boot-project/spring-boot/src/test/java/org/springframework/boot/context/properties/ConfigurationPropertiesTests.java b/spring-boot-project/spring-boot/src/test/java/org/springframework/boot/context/properties/ConfigurationPropertiesTests.java
index 2e2c22377472..ee5b68be1656 100644
--- a/spring-boot-project/spring-boot/src/test/java/org/springframework/boot/context/properties/ConfigurationPropertiesTests.java
+++ b/spring-boot-project/spring-boot/src/test/java/org/springframework/boot/context/properties/ConfigurationPropertiesTests.java
@@ -679,6 +679,20 @@ void loadWhenBeanFactoryConversionServiceAndConverterBeanCanUseConverterBean() {
 		assertThat(properties.getAlien().name).isEqualTo("rennaT flA");
 	}
 
+	@Test // gh-38734
+	void loadWhenBeanFactoryConversionServiceAndConverterBeanCanUseConverterBeanWithCollections() {
+		DefaultConversionService conversionService = new DefaultConversionService();
+		conversionService.addConverter(new PersonConverter());
+		this.context.getBeanFactory().setConversionService(conversionService);
+		load(new Class<?>[] { AlienConverterConfiguration.class, PersonAndAliensProperties.class },
+				"test.person=John Smith", "test.aliens=Alf Tanner,Gilbert");
+		PersonAndAliensProperties properties = this.context.getBean(PersonAndAliensProperties.class);
+		assertThat(properties.getPerson().firstName).isEqualTo("John");
+		assertThat(properties.getPerson().lastName).isEqualTo("Smith");
+		assertThat(properties.getAliens().get(0).name).isEqualTo("rennaT flA");
+		assertThat(properties.getAliens().get(1).name).isEqualTo("trebliG");
+	}
+
 	@Test
 	void loadWhenConfigurationConverterIsNotQualifiedShouldNotConvert() {
 		assertThatExceptionOfType(BeanCreationException.class)
@@ -2090,6 +2104,32 @@ void setAlien(Alien alien) {
 
 	}
 
+	@EnableConfigurationProperties
+	@ConfigurationProperties(prefix = "test")
+	static class PersonAndAliensProperties {
+
+		private Person person;
+
+		private List<Alien> aliens;
+
+		Person getPerson() {
+			return this.person;
+		}
+
+		void setPerson(Person person) {
+			this.person = person;
+		}
+
+		List<Alien> getAliens() {
+			return this.aliens;
+		}
+
+		void setAliens(List<Alien> aliens) {
+			this.aliens = aliens;
+		}
+
+	}
+
 	@EnableConfigurationProperties
 	@ConfigurationProperties(prefix = "sample")
 	static class MapWithNumericKeyProperties {