Enforce that '@ConfigurationPropertiesBinding' bean methods are static

buildSrc/src/main/java/org/springframework/boot/build/architecture/ArchitectureRules.java

@@ -64,6 +64,7 @@
  * @author Scott Frederick
  * @author Ivan Malutin
  * @author Phillip Webb
+ * @author Ngoc Nhan
  */
 final class ArchitectureRules {
 
@@ -96,6 +97,7 @@ static List<ArchRule> standard() {
 		rules.add(classLevelConfigurationPropertiesShouldNotSpecifyOnlyPrefixAttribute());
 		rules.add(methodLevelConfigurationPropertiesShouldNotSpecifyOnlyPrefixAttribute());
 		rules.add(conditionsShouldNotBePublic());
+		rules.add(allConfigurationPropertiesBindingBeanMethodsShouldBeStatic());
 		return List.copyOf(rules);
 	}
 
@@ -309,6 +311,14 @@ private static ArchRule conditionsShouldNotBePublic() {
 			.allowEmptyShould(true);
 	}
 
+	private static ArchRule allConfigurationPropertiesBindingBeanMethodsShouldBeStatic() {
+		return methodsThatAreAnnotatedWith("org.springframework.context.annotation.Bean").and()
+			.areAnnotatedWith("org.springframework.boot.context.properties.ConfigurationPropertiesBinding")
+			.should()
+			.beStatic()
+			.allowEmptyShould(true);
+	}
+
 	private static boolean containsOnlySingleType(JavaType[] types, JavaType type) {
 		return types.length == 1 && type.equals(types[0]);
 	}

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/flyway/FlywayAutoConfiguration.java

@@ -113,7 +113,7 @@ public class FlywayAutoConfiguration {
 
 	@Bean
 	@ConfigurationPropertiesBinding
-	public StringOrNumberToMigrationVersionConverter stringOrNumberMigrationVersionConverter() {
+	public static StringOrNumberToMigrationVersionConverter stringOrNumberMigrationVersionConverter() {
 		return new StringOrNumberToMigrationVersionConverter();
 	}
 

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/security/servlet/SecurityAutoConfigurationTests.java

@@ -264,7 +264,7 @@ static class ConverterConfiguration {
 
 		@Bean
 		@ConfigurationPropertiesBinding
-		Converter<String, TargetType> targetTypeConverter() {
+		static Converter<String, TargetType> targetTypeConverter() {
 			return new Converter<>() {
 
 				@Override

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/context/properties/ConfigurationPropertiesTests.java

@@ -1593,7 +1593,7 @@ static class PersonConverterConfiguration {
 
 		@Bean
 		@ConfigurationPropertiesBinding
-		Converter<String, Person> personConverter() {
+		static Converter<String, Person> personConverter() {
 			return new PersonConverter();
 		}
 
@@ -1604,7 +1604,7 @@ static class AlienConverterConfiguration {
 
 		@Bean
 		@ConfigurationPropertiesBinding
-		Converter<String, Alien> alienConverter() {
+		static Converter<String, Alien> alienConverter() {
 			return new AlienConverter();
 		}
 
@@ -1625,7 +1625,7 @@ static class GenericConverterConfiguration {
 
 		@Bean
 		@ConfigurationPropertiesBinding
-		GenericConverter genericPersonConverter() {
+		static GenericConverter genericPersonConverter() {
 			return new GenericPersonConverter();
 		}
 
@@ -1636,7 +1636,7 @@ static class FormatterConfiguration {
 
 		@Bean
 		@ConfigurationPropertiesBinding
-		Formatter<Person> personFormatter() {
+		static Formatter<Person> personFormatter() {
 			return new PersonFormatter();
 		}
 
@@ -3064,7 +3064,7 @@ static class WithCustomConverterAndObjectToObjectMethodConfiguration {
 
 		@Bean
 		@ConfigurationPropertiesBinding
-		WithObjectToObjectMethodConverter withObjectToObjectMethodConverter() {
+		static WithObjectToObjectMethodConverter withObjectToObjectMethodConverter() {
 			return new WithObjectToObjectMethodConverter();
 		}
 

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/context/properties/ConversionServiceDeducerTests.java

@@ -129,13 +129,13 @@ static class CustomConverterConfiguration {
 
 		@Bean
 		@ConfigurationPropertiesBinding
-		TestConverter testConverter() {
+		static TestConverter testConverter() {
 			return new TestConverter();
 		}
 
 		@Bean
 		@ConfigurationPropertiesBinding
-		StringConverter stringConverter() {
+		static StringConverter stringConverter() {
 			return new StringConverter();
 		}
 
@@ -146,13 +146,13 @@ static class CustomLambdaConverterConfiguration {
 
 		@Bean
 		@ConfigurationPropertiesBinding
-		Converter<InputStream, OutputStream> testConverter() {
+		static Converter<InputStream, OutputStream> testConverter() {
 			return (source) -> new TestConverter().convert(source);
 		}
 
 		@Bean
 		@ConfigurationPropertiesBinding
-		Converter<String, InputStream> stringConverter() {
+		static Converter<String, InputStream> stringConverter() {
 			return (source) -> new StringConverter().convert(source);
 		}
 
@@ -163,7 +163,7 @@ static class PrinterConfiguration {
 
 		@Bean
 		@ConfigurationPropertiesBinding
-		Printer<InputStream> inputStreamPrinter() {
+		static Printer<InputStream> inputStreamPrinter() {
 			return (source, locale) -> ThrowingSupplier
 				.of(() -> StreamUtils.copyToString(source, StandardCharsets.UTF_8))
 				.get();