Merge branch '3.3.x'

Closes gh-42736

buildSrc/src/main/java/org/springframework/boot/build/antora/AntoraAsciidocAttributes.java

@@ -191,7 +191,8 @@ public synchronized Object put(Object key, Object value) {
 		};
 		try (InputStream in = getClass().getResourceAsStream("antora-asciidoc-attributes.properties")) {
 			properties.load(in);
-		} catch (IOException ex) {
+		}
+		catch (IOException ex) {
 			throw new UncheckedIOException(ex);
 		}
 	}

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2022-2024 the original author or authors.
+ * Copyright 2012-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -89,7 +89,8 @@ public ArchitectureCheck() {
 				noClassesShouldCallStepVerifierStepVerifyComplete(),
 				noClassesShouldConfigureDefaultStepVerifierTimeout(), noClassesShouldCallCollectorsToList(),
 				noClassesShouldCallURLEncoderWithStringEncoding(), noClassesShouldCallURLDecoderWithStringEncoding(),
-				noClassesShouldLoadResourcesUsingResourceUtils());
+				noClassesShouldLoadResourcesUsingResourceUtils(), noClassesShouldCallStringToUpperCaseWithoutLocale(),
+				noClassesShouldCallStringToLowerCaseWithoutLocale());
 		getRules().addAll(getProhibitObjectsRequireNonNull()
 			.map((prohibit) -> prohibit ? noClassesShouldCallObjectsRequireNonNull() : Collections.emptyList()));
 		getRuleDescriptions().set(getRules().map((rules) -> rules.stream().map(ArchRule::getDescription).toList()));
@@ -191,6 +192,20 @@ public void check(JavaMethod item, ConditionEvents events) {
 		};
 	}
 
+	private ArchRule noClassesShouldCallStringToLowerCaseWithoutLocale() {
+		return ArchRuleDefinition.noClasses()
+			.should()
+			.callMethod(String.class, "toLowerCase")
+			.because("String.toLowerCase(Locale.ROOT) should be used instead");
+	}
+
+	private ArchRule noClassesShouldCallStringToUpperCaseWithoutLocale() {
+		return ArchRuleDefinition.noClasses()
+			.should()
+			.callMethod(String.class, "toUpperCase")
+			.because("String.toUpperCase(Locale.ROOT) should be used instead");
+	}
+
 	private ArchRule noClassesShouldCallStepVerifierStepVerifyComplete() {
 		return ArchRuleDefinition.noClasses()
 			.should()

buildSrc/src/main/java/org/springframework/boot/build/artifacts/ArtifactRelease.java

@@ -16,6 +16,8 @@
 
 package org.springframework.boot.build.artifacts;
 
+import java.util.Locale;
+
 import org.gradle.api.Project;
 
 /**
@@ -37,7 +39,7 @@ private ArtifactRelease(Type type) {
 	}
 
 	public String getType() {
-		return this.type.toString().toLowerCase();
+		return this.type.toString().toLowerCase(Locale.ROOT);
 	}
 
 	public String getDownloadRepo() {

buildSrc/src/main/java/org/springframework/boot/build/bom/Library.java

@@ -102,7 +102,7 @@ public Library(String name, String calendarName, LibraryVersion version, List<Gr
 	}
 
 	private static String generateLinkRootName(String name) {
-		return name.replace("-", "").replace(" ", "-").toLowerCase();
+		return name.replace("-", "").replace(" ", "-").toLowerCase(Locale.ROOT);
 	}
 
 	public String getName() {

buildSrc/src/main/java/org/springframework/boot/build/properties/BuildType.java

@@ -16,6 +16,8 @@
 
 package org.springframework.boot.build.properties;
 
+import java.util.Locale;
+
 /**
  * The type of build being performed.
  *
@@ -34,7 +36,7 @@ public enum BuildType {
 	COMMERCIAL;
 
 	public String toIdentifier() {
-		return toString().replace("_", "").toLowerCase();
+		return toString().replace("_", "").toLowerCase(Locale.ROOT);
 	}
 
 }

buildSrc/src/test/java/org/springframework/boot/build/architecture/ArchitectureCheckTests.java

@@ -163,6 +163,42 @@ void whenClassCallsObjectsRequireNonNullWithSupplierTaskFailsAndWritesReport() t
 		});
 	}
 
+	@Test
+	void whenClassCallsStringToUpperCaseWithoutLocaleFailsAndWritesReport() throws Exception {
+		prepareTask("string/toUpperCase", (architectureCheck) -> {
+			assertThatExceptionOfType(GradleException.class).isThrownBy(architectureCheck::checkArchitecture);
+			assertThat(failureReport(architectureCheck)).isNotEmpty()
+				.content()
+				.contains("because String.toUpperCase(Locale.ROOT) should be used instead");
+		});
+	}
+
+	@Test
+	void whenClassCallsStringToLowerCaseWithoutLocaleFailsAndWritesReport() throws Exception {
+		prepareTask("string/toLowerCase", (architectureCheck) -> {
+			assertThatExceptionOfType(GradleException.class).isThrownBy(architectureCheck::checkArchitecture);
+			assertThat(failureReport(architectureCheck)).isNotEmpty()
+				.content()
+				.contains("because String.toLowerCase(Locale.ROOT) should be used instead");
+		});
+	}
+
+	@Test
+	void whenClassCallsStringToLowerCaseWithLocaleShouldNotFail() throws Exception {
+		prepareTask("string/toLowerCaseWithLocale", (architectureCheck) -> {
+			architectureCheck.checkArchitecture();
+			assertThat(failureReport(architectureCheck)).isEmpty();
+		});
+	}
+
+	@Test
+	void whenClassCallsStringToUpperCaseWithLocaleShouldNotFail() throws Exception {
+		prepareTask("string/toUpperCaseWithLocale", (architectureCheck) -> {
+			architectureCheck.checkArchitecture();
+			assertThat(failureReport(architectureCheck)).isEmpty();
+		});
+	}
+
 	private void prepareTask(String classes, Callback<ArchitectureCheck> callback) throws Exception {
 		File projectDir = new File(this.temp, "project");
 		projectDir.mkdirs();

buildSrc/src/test/java/org/springframework/boot/build/architecture/string/toLowerCase/ToLowerCase.java

@@ -0,0 +1,26 @@
+/*
+ * Copyright 2012-2024 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.build.architecture.string.toLowerCase;
+
+class ToLowerCase {
+
+	void exampleMethod() {
+		String test = "Object must not be null";
+		System.out.println(test.toLowerCase());
+	}
+
+}

buildSrc/src/test/java/org/springframework/boot/build/architecture/string/toLowerCaseWithLocale/ToLowerCaseWithLocale.java

@@ -0,0 +1,28 @@
+/*
+ * Copyright 2012-2024 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.build.architecture.string.toLowerCaseWithLocale;
+
+import java.util.Locale;
+
+class ToLowerCaseWithLocale {
+
+	void exampleMethod() {
+		String test = "Object must not be null";
+		System.out.println(test.toLowerCase(Locale.ENGLISH));
+	}
+
+}

buildSrc/src/test/java/org/springframework/boot/build/architecture/string/toUpperCase/ToUpperCase.java

@@ -0,0 +1,26 @@
+/*
+ * Copyright 2012-2024 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.build.architecture.string.toUpperCase;
+
+class ToUpperCase {
+
+	void exampleMethod() {
+		String test = "Object must not be null";
+		System.out.println(test.toUpperCase());
+	}
+
+}

buildSrc/src/test/java/org/springframework/boot/build/architecture/string/toUpperCaseWithLocale/ToUpperCaseWithLocale.java

@@ -0,0 +1,28 @@
+/*
+ * Copyright 2012-2024 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.build.architecture.string.toUpperCaseWithLocale;
+
+import java.util.Locale;
+
+class ToUpperCaseWithLocale {
+
+	void exampleMethod() {
+		String test = "Object must not be null";
+		System.out.println(test.toUpperCase(Locale.ROOT));
+	}
+
+}

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/endpoint/condition/OnAvailableEndpointCondition.java

@@ -21,6 +21,7 @@
 import java.util.EnumSet;
 import java.util.LinkedHashSet;
 import java.util.List;
+import java.util.Locale;
 import java.util.Map;
 import java.util.Optional;
 import java.util.Set;
@@ -206,7 +207,7 @@ private static class StandardExposureOutcomeContributor implements EndpointExpos
 
 		StandardExposureOutcomeContributor(Environment environment, EndpointExposure exposure) {
 			this.exposure = exposure;
-			String name = exposure.name().toLowerCase().replace('_', '-');
+			String name = exposure.name().toLowerCase(Locale.ROOT).replace('_', '-');
 			this.property = "management.endpoints." + name + ".exposure";
 			this.filter = new IncludeExcludeEndpointFilter<>(ExposableEndpoint.class, environment, this.property,
 					exposure.getDefaultIncludes());

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/tracing/otlp/OtlpTracingConfigurations.java

@@ -16,6 +16,8 @@
 
 package org.springframework.boot.actuate.autoconfigure.tracing.otlp;
 
+import java.util.Locale;
+
 import io.opentelemetry.exporter.otlp.http.trace.OtlpHttpSpanExporter;
 import io.opentelemetry.exporter.otlp.http.trace.OtlpHttpSpanExporterBuilder;
 import io.opentelemetry.exporter.otlp.trace.OtlpGrpcSpanExporter;
@@ -85,7 +87,7 @@ OtlpHttpSpanExporter otlpHttpSpanExporter(OtlpTracingProperties properties,
 				.setEndpoint(connectionDetails.getUrl(Transport.HTTP))
 				.setTimeout(properties.getTimeout())
 				.setConnectTimeout(properties.getConnectTimeout())
-				.setCompression(properties.getCompression().name().toLowerCase());
+				.setCompression(properties.getCompression().name().toLowerCase(Locale.ROOT));
 			properties.getHeaders().forEach(builder::addHeader);
 			return builder.build();
 		}
@@ -98,7 +100,7 @@ OtlpGrpcSpanExporter otlpGrpcSpanExporter(OtlpTracingProperties properties,
 				.setEndpoint(connectionDetails.getUrl(Transport.GRPC))
 				.setTimeout(properties.getTimeout())
 				.setConnectTimeout(properties.getConnectTimeout())
-				.setCompression(properties.getCompression().name().toLowerCase());
+				.setCompression(properties.getCompression().name().toLowerCase(Locale.ROOT));
 			properties.getHeaders().forEach(builder::addHeader);
 			return builder.build();
 		}

spring-boot-project/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/web/exchanges/HttpExchange.java

@@ -25,6 +25,7 @@
 import java.util.HashSet;
 import java.util.LinkedHashMap;
 import java.util.List;
+import java.util.Locale;
 import java.util.Map;
 import java.util.Set;
 import java.util.function.Supplier;
@@ -434,7 +435,7 @@ private static class HeadersFilter {
 
 		void excludeUnless(String header, Include exception) {
 			if (!this.includes.contains(exception)) {
-				this.filteredHeaderNames.add(header.toLowerCase());
+				this.filteredHeaderNames.add(header.toLowerCase(Locale.ROOT));
 			}
 		}
 
@@ -444,7 +445,7 @@ Map<String, List<String>> apply(Map<String, List<String>> headers) {
 			}
 			Map<String, List<String>> filtered = new LinkedHashMap<>();
 			headers.forEach((name, value) -> {
-				if (!this.filteredHeaderNames.contains(name.toLowerCase())) {
+				if (!this.filteredHeaderNames.contains(name.toLowerCase(Locale.ROOT))) {
 					filtered.put(name, value);
 				}
 			});

spring-boot-project/spring-boot-actuator/src/test/java/org/springframework/boot/actuate/endpoint/annotation/DiscoveredOperationMethodTests.java

@@ -17,6 +17,7 @@
 package org.springframework.boot.actuate.endpoint.annotation;
 
 import java.lang.reflect.Method;
+import java.util.Locale;
 
 import org.junit.jupiter.api.Test;
 
@@ -76,7 +77,7 @@ enum ExampleProducible implements Producible<ExampleProducible> {
 
 		@Override
 		public MimeType getProducedMimeType() {
-			return new MimeType(toString().toLowerCase());
+			return new MimeType(toString().toLowerCase(Locale.ROOT));
 		}
 
 	}

spring-boot-project/spring-boot-actuator/src/test/java/org/springframework/boot/actuate/endpoint/annotation/DiscoveredOperationsFactoryTests.java

@@ -20,6 +20,7 @@
 import java.util.Collection;
 import java.util.Collections;
 import java.util.List;
+import java.util.Locale;
 import java.util.Map;
 
 import org.junit.jupiter.api.BeforeEach;
@@ -254,7 +255,7 @@ enum ExampleProducible implements Producible<ExampleProducible> {
 
 		@Override
 		public MimeType getProducedMimeType() {
-			return new MimeType(toString().toLowerCase());
+			return new MimeType(toString().toLowerCase(Locale.ROOT));
 		}
 
 	}

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/hazelcast/PropertiesHazelcastConnectionDetails.java

@@ -19,6 +19,7 @@
 import java.io.IOException;
 import java.io.UncheckedIOException;
 import java.net.URL;
+import java.util.Locale;
 
 import com.hazelcast.client.config.ClientConfig;
 import com.hazelcast.client.config.XmlClientConfigBuilder;
@@ -54,7 +55,7 @@ public ClientConfig getClientConfig() {
 	private ClientConfig loadClientConfig(Resource configLocation) {
 		try {
 			URL configUrl = configLocation.getURL();
-			String configFileName = configUrl.getPath().toLowerCase();
+			String configFileName = configUrl.getPath().toLowerCase(Locale.ROOT);
 			return (!isYaml(configFileName)) ? new XmlClientConfigBuilder(configUrl).build()
 					: new YamlClientConfigBuilder(configUrl).build();
 		}

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/security/oauth2/server/servlet/OAuth2AuthorizationServerPropertiesMapper.java

@@ -18,6 +18,7 @@
 
 import java.util.ArrayList;
 import java.util.List;
+import java.util.Locale;
 
 import org.springframework.boot.autoconfigure.security.oauth2.server.servlet.OAuth2AuthorizationServerProperties.Client;
 import org.springframework.boot.autoconfigure.security.oauth2.server.servlet.OAuth2AuthorizationServerProperties.Registration;
@@ -124,7 +125,7 @@ private TokenSettings getTokenSettings(Client client, PropertyMapper map) {
 	}
 
 	private JwsAlgorithm jwsAlgorithm(String signingAlgorithm) {
-		String name = signingAlgorithm.toUpperCase();
+		String name = signingAlgorithm.toUpperCase(Locale.ROOT);
 		JwsAlgorithm jwsAlgorithm = SignatureAlgorithm.from(name);
 		if (jwsAlgorithm == null) {
 			jwsAlgorithm = MacAlgorithm.from(name);
@@ -133,7 +134,7 @@ private JwsAlgorithm jwsAlgorithm(String signingAlgorithm) {
 	}
 
 	private SignatureAlgorithm signatureAlgorithm(String signatureAlgorithm) {
-		return SignatureAlgorithm.from(signatureAlgorithm.toUpperCase());
+		return SignatureAlgorithm.from(signatureAlgorithm.toUpperCase(Locale.ROOT));
 	}
 
 }