Use a single customizer property for JSON logging

Update `StructuredLoggingJsonProperties` no that only a single
`customizer` property is supported.

See gh-43368

Author: philwebb

spring-boot-project/spring-boot-docs/src/docs/antora/modules/reference/pages/features/logging.adoc

@@ -642,7 +642,7 @@ logging:
 ----
 
 TIP: For more advanced customizations, you can use the javadoc:org.springframework.boot.logging.structured.StructuredLoggingJsonMembersCustomizer[] interface.
-You can reference a single implementation using the configprop:logging.structured.json.customizer[] property, or use configprop:logging.structured.json.customizers[] if you have more than one.
+You can reference a one or more implementations using the configprop:logging.structured.json.customizer[] property.
 You can also declare implementations by listing them in a `META-INF/spring.factories` file.
 
 

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/logging/structured/StructuredLoggingJsonMembersCustomizerBeanFactoryInitializationAotProcessor.java

@@ -45,7 +45,7 @@ class StructuredLoggingJsonMembersCustomizerBeanFactoryInitializationAotProcesso
 	public BeanFactoryInitializationAotContribution processAheadOfTime(ConfigurableListableBeanFactory beanFactory) {
 		Environment environment = beanFactory.getBean(ENVIRONMENT_BEAN_NAME, Environment.class);
 		StructuredLoggingJsonProperties properties = StructuredLoggingJsonProperties.get(environment);
-		return (properties != null) ? AotContribution.get(properties.allCustomizers()) : null;
+		return (properties != null) ? AotContribution.get(properties.customizer()) : null;
 	}
 
 	private static final class AotContribution implements BeanFactoryInitializationAotContribution {

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/logging/structured/StructuredLoggingJsonProperties.java

@@ -18,15 +18,14 @@
 
 import java.util.Collection;
 import java.util.Collections;
-import java.util.LinkedHashSet;
+import java.util.List;
 import java.util.Map;
 import java.util.Set;
 
 import org.springframework.boot.context.properties.bind.BindableRuntimeHintsRegistrar;
 import org.springframework.boot.context.properties.bind.Binder;
 import org.springframework.boot.util.Instantiator;
 import org.springframework.core.env.Environment;
-import org.springframework.util.CollectionUtils;
 
 /**
  * Properties that can be used to customize structured logging JSON.
@@ -35,42 +34,21 @@
  * @param exclude the paths that should be excluded. An empty set excludes nothing
  * @param rename a map of path to replacement names
  * @param add a map of additional elements {@link StructuredLoggingJsonMembersCustomizer}
- * @param customizer the fully qualified name of a
- * {@link StructuredLoggingJsonMembersCustomizer} implementation
- * @param customizers the fully qualified names of
+ * @param customizer the fully qualified names of
  * {@link StructuredLoggingJsonMembersCustomizer} implementations
  * @author Phillip Webb
  * @author Yanming Zhou
  */
 record StructuredLoggingJsonProperties(Set<String> include, Set<String> exclude, Map<String, String> rename,
-		Map<String, String> add, Class<? extends StructuredLoggingJsonMembersCustomizer<?>> customizer,
-		Set<Class<? extends StructuredLoggingJsonMembersCustomizer<?>>> customizers) {
+		Map<String, String> add, Set<Class<? extends StructuredLoggingJsonMembersCustomizer<?>>> customizer) {
 
-	Collection<StructuredLoggingJsonMembersCustomizer<Object>> allCustomizers(Instantiator<?> instantiator) {
-		return allCustomizers().stream().map((customizer) -> instantiateCustomizer(instantiator, customizer)).toList();
+	StructuredLoggingJsonProperties {
+		customizer = (customizer != null) ? customizer : Collections.emptySet();
 	}
 
-	Set<Class<? extends StructuredLoggingJsonMembersCustomizer<?>>> allCustomizers() {
-		return merge(customizer(), customizers());
-	}
-
-	private <T> Set<T> merge(T element, Set<T> elements) {
-		if (CollectionUtils.isEmpty(elements)) {
-			return (element != null) ? Set.of(element) : Collections.emptySet();
-		}
-		if (element == null) {
-			return elements;
-		}
-		Set<T> result = new LinkedHashSet<>(elements.size() + 1);
-		result.add(element);
-		result.addAll(elements);
-		return result;
-	}
-
-	@SuppressWarnings("unchecked")
-	private StructuredLoggingJsonMembersCustomizer<Object> instantiateCustomizer(Instantiator<?> instantiator,
-			Class<? extends StructuredLoggingJsonMembersCustomizer<?>> customizer) {
-		return (StructuredLoggingJsonMembersCustomizer<Object>) instantiator.instantiateType(customizer);
+	@SuppressWarnings({ "unchecked", "rawtypes" })
+	Collection<StructuredLoggingJsonMembersCustomizer<Object>> customizers(Instantiator<?> instantiator) {
+		return (List) customizer().stream().map(instantiator::instantiateType).toList();
 	}
 
 	static StructuredLoggingJsonProperties get(Environment environment) {

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/logging/structured/StructuredLoggingJsonPropertiesJsonMembersCustomizer.java

@@ -50,7 +50,7 @@ public void customize(Members<Object> members) {
 		if (!CollectionUtils.isEmpty(add)) {
 			add.forEach(members::add);
 		}
-		this.properties.allCustomizers(this.instantiator).forEach((customizer) -> customizer.customize(members));
+		this.properties.customizers(this.instantiator).forEach((customizer) -> customizer.customize(members));
 	}
 
 	String renameJsonMembers(MemberPath path, String existingName) {

spring-boot-project/spring-boot/src/main/resources/META-INF/additional-spring-configuration-metadata.json

@@ -266,15 +266,10 @@
       "type": "java.util.Map<java.lang.String,java.lang.String>",
       "description": "Additional members that should be added to structured logging JSON"
     },
-    {
-      "name": "logging.structured.json.customizer",
-      "type": "java.lang.Class<? extends org.springframework.boot.logging.structured.StructuredLoggingJsonMembersCustomizer<?>>",
-      "description": "The fully qualified class name of a StructuredLoggingJsonMembersCustomizer"
-    },
     {
       "name": "logging.structured.json.customizers",
       "type": "java.util.Set<java.lang.Class<? extends org.springframework.boot.logging.structured.StructuredLoggingJsonMembersCustomizer<?>>>",
-      "description": "The fully qualified class names of a StructuredLoggingJsonMembersCustomizer"
+      "description": "Fully qualified class names of StructuredLoggingJsonMembersCustomizer implementations"
     },
     {
       "name": "logging.structured.json.exclude",

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/logging/structured/StructuredLoggingJsonPropertiesJsonMembersCustomizerTests.java

@@ -48,7 +48,7 @@ class StructuredLoggingJsonPropertiesJsonMembersCustomizerTests {
 	@Test
 	void customizeWhenHasExcludeFiltersMember() {
 		StructuredLoggingJsonProperties properties = new StructuredLoggingJsonProperties(Collections.emptySet(),
-				Set.of("a"), Collections.emptyMap(), Collections.emptyMap(), null, null);
+				Set.of("a"), Collections.emptyMap(), Collections.emptyMap(), null);
 		StructuredLoggingJsonPropertiesJsonMembersCustomizer customizer = new StructuredLoggingJsonPropertiesJsonMembersCustomizer(
 				this.instantiator, properties);
 		assertThat(writeSampleJson(customizer)).doesNotContain("a").contains("b");
@@ -57,7 +57,7 @@ void customizeWhenHasExcludeFiltersMember() {
 	@Test
 	void customizeWhenHasIncludeFiltersOtherMembers() {
 		StructuredLoggingJsonProperties properties = new StructuredLoggingJsonProperties(Set.of("a"),
-				Collections.emptySet(), Collections.emptyMap(), Collections.emptyMap(), null, null);
+				Collections.emptySet(), Collections.emptyMap(), Collections.emptyMap(), null);
 		StructuredLoggingJsonPropertiesJsonMembersCustomizer customizer = new StructuredLoggingJsonPropertiesJsonMembersCustomizer(
 				this.instantiator, properties);
 		assertThat(writeSampleJson(customizer)).contains("a")
@@ -69,7 +69,7 @@ void customizeWhenHasIncludeFiltersOtherMembers() {
 	@Test
 	void customizeWhenHasIncludeAndExcludeFiltersMembers() {
 		StructuredLoggingJsonProperties properties = new StructuredLoggingJsonProperties(Set.of("a", "b"), Set.of("b"),
-				Collections.emptyMap(), Collections.emptyMap(), null, null);
+				Collections.emptyMap(), Collections.emptyMap(), null);
 		StructuredLoggingJsonPropertiesJsonMembersCustomizer customizer = new StructuredLoggingJsonPropertiesJsonMembersCustomizer(
 				this.instantiator, properties);
 		assertThat(writeSampleJson(customizer)).contains("a")
@@ -81,7 +81,7 @@ void customizeWhenHasIncludeAndExcludeFiltersMembers() {
 	@Test
 	void customizeWhenHasRenameRenamesMember() {
 		StructuredLoggingJsonProperties properties = new StructuredLoggingJsonProperties(Collections.emptySet(),
-				Collections.emptySet(), Map.of("a", "z"), Collections.emptyMap(), null, null);
+				Collections.emptySet(), Map.of("a", "z"), Collections.emptyMap(), null);
 		StructuredLoggingJsonPropertiesJsonMembersCustomizer customizer = new StructuredLoggingJsonPropertiesJsonMembersCustomizer(
 				this.instantiator, properties);
 		assertThat(writeSampleJson(customizer)).contains("\"z\":\"a\"");
@@ -90,7 +90,7 @@ void customizeWhenHasRenameRenamesMember() {
 	@Test
 	void customizeWhenHasAddAddsMemeber() {
 		StructuredLoggingJsonProperties properties = new StructuredLoggingJsonProperties(Collections.emptySet(),
-				Collections.emptySet(), Collections.emptyMap(), Map.of("z", "z"), null, null);
+				Collections.emptySet(), Collections.emptyMap(), Map.of("z", "z"), null);
 		StructuredLoggingJsonPropertiesJsonMembersCustomizer customizer = new StructuredLoggingJsonPropertiesJsonMembersCustomizer(
 				this.instantiator, properties);
 		assertThat(writeSampleJson(customizer)).contains("\"z\":\"z\"");
@@ -103,7 +103,7 @@ void customizeWhenHasCustomizerCustomizesMember() {
 			.applyingNameProcessor(NameProcessor.of(String::toUpperCase));
 		given(((Instantiator) this.instantiator).instantiateType(TestCustomizer.class)).willReturn(uppercaseCustomizer);
 		StructuredLoggingJsonProperties properties = new StructuredLoggingJsonProperties(Collections.emptySet(),
-				Collections.emptySet(), Collections.emptyMap(), Collections.emptyMap(), TestCustomizer.class, null);
+				Collections.emptySet(), Collections.emptyMap(), Collections.emptyMap(), Set.of(TestCustomizer.class));
 		StructuredLoggingJsonPropertiesJsonMembersCustomizer customizer = new StructuredLoggingJsonPropertiesJsonMembersCustomizer(
 				this.instantiator, properties);
 		assertThat(writeSampleJson(customizer)).contains("\"A\":\"a\"");
@@ -115,26 +115,13 @@ void customizeWhenHasCustomizersCustomizesMember() {
 		given(((Instantiator) this.instantiator).instantiateType(FooCustomizer.class)).willReturn(new FooCustomizer());
 		given(((Instantiator) this.instantiator).instantiateType(BarCustomizer.class)).willReturn(new BarCustomizer());
 		StructuredLoggingJsonProperties properties = new StructuredLoggingJsonProperties(Collections.emptySet(),
-				Collections.emptySet(), Collections.emptyMap(), Collections.emptyMap(), null,
+				Collections.emptySet(), Collections.emptyMap(), Collections.emptyMap(),
 				Set.of(FooCustomizer.class, BarCustomizer.class));
 		StructuredLoggingJsonPropertiesJsonMembersCustomizer customizer = new StructuredLoggingJsonPropertiesJsonMembersCustomizer(
 				this.instantiator, properties);
 		assertThat(writeSampleJson(customizer)).contains("\"foo\":\"foo\"").contains("\"bar\":\"bar\"");
 	}
 
-	@Test
-	@SuppressWarnings({ "rawtypes", "unchecked" })
-	void customizeWhenHasCustomizerAndCustomizersCustomizesMember() {
-		given(((Instantiator) this.instantiator).instantiateType(FooCustomizer.class)).willReturn(new FooCustomizer());
-		given(((Instantiator) this.instantiator).instantiateType(BarCustomizer.class)).willReturn(new BarCustomizer());
-		StructuredLoggingJsonProperties properties = new StructuredLoggingJsonProperties(Collections.emptySet(),
-				Collections.emptySet(), Collections.emptyMap(), Collections.emptyMap(), FooCustomizer.class,
-				Set.of(BarCustomizer.class));
-		StructuredLoggingJsonPropertiesJsonMembersCustomizer customizer = new StructuredLoggingJsonPropertiesJsonMembersCustomizer(
-				this.instantiator, properties);
-		assertThat(writeSampleJson(customizer)).contains("\"foo\":\"foo\"").contains("\"bar\":\"bar\"");
-	}
-
 	@SuppressWarnings({ "rawtypes", "unchecked" })
 	private String writeSampleJson(StructuredLoggingJsonMembersCustomizer customizer) {
 		return JsonWriter.of((members) -> {

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/logging/structured/StructuredLoggingJsonPropertiesTests.java

@@ -48,7 +48,7 @@ void getBindsFromEnvironment() {
 		environment.setProperty("logging.structured.json.customizer", TestCustomizer.class.getName());
 		StructuredLoggingJsonProperties properties = StructuredLoggingJsonProperties.get(environment);
 		assertThat(properties).isEqualTo(new StructuredLoggingJsonProperties(Set.of("a", "b"), Set.of("c", "d"),
-				Map.of("e", "f"), Map.of("g", "h"), TestCustomizer.class, null));
+				Map.of("e", "f"), Map.of("g", "h"), Set.of(TestCustomizer.class)));
 	}
 
 	@Test
@@ -64,7 +64,7 @@ void shouldRegisterRuntimeHints() throws Exception {
 		assertThat(RuntimeHintsPredicates.reflection().onType(StructuredLoggingJsonProperties.class)).accepts(hints);
 		assertThat(RuntimeHintsPredicates.reflection()
 			.onConstructor(StructuredLoggingJsonProperties.class.getDeclaredConstructor(Set.class, Set.class, Map.class,
-					Map.class, Class.class, Set.class))
+					Map.class, Set.class))
 			.invoke()).accepts(hints);
 	}