Only support `@OptionalParameter` annotation with endpoint methods

Remove `@Nullable` support for optional endpoint method parameters in
favor of only supporting `@OptionalParameter`. The annotation processor
now also only supports `@OptionalParameter` detection.

Closes gh-47136

configuration-metadata/spring-boot-configuration-processor/src/main/java/org/springframework/boot/configurationprocessor/ConfigurationMetadataAnnotationProcessor.java

@@ -107,9 +107,9 @@ public class ConfigurationMetadataAnnotationProcessor extends AbstractProcessor
 
 	static final String WEB_ENDPOINT_ANNOTATION = "org.springframework.boot.actuate.endpoint.web.annotation.WebEndpoint";
 
-	static final String READ_OPERATION_ANNOTATION = "org.springframework.boot.actuate.endpoint.annotation.ReadOperation";
+	static final String ENDPOINT_READ_OPERATION_ANNOTATION = "org.springframework.boot.actuate.endpoint.annotation.ReadOperation";
 
-	static final String OPTIONAL_PARAMETER_ANNOTATION = "org.springframework.boot.actuate.endpoint.annotation.OptionalParameter";
+	static final String ENDPOINT_OPTIONAL_PARAMETER_ANNOTATION = "org.springframework.boot.actuate.endpoint.annotation.OptionalParameter";
 
 	static final String NAME_ANNOTATION = "org.springframework.boot.context.properties.bind.Name";
 
@@ -158,16 +158,16 @@ public class ConfigurationMetadataAnnotationProcessor extends AbstractProcessor
 				REST_CONTROLLER_ENDPOINT_ANNOTATION, SERVLET_ENDPOINT_ANNOTATION, WEB_ENDPOINT_ANNOTATION);
 	}
 
-	protected String readOperationAnnotation() {
+	protected String endpointReadOperationAnnotation() {
-		return READ_OPERATION_ANNOTATION;
+		return ENDPOINT_READ_OPERATION_ANNOTATION;
 	}
 
 	protected String nameAnnotation() {
 		return NAME_ANNOTATION;
 	}
 
-	protected String optionalParameterAnnotation() {
+	protected String endpointOptionalParameterAnnotation() {
-		return OPTIONAL_PARAMETER_ANNOTATION;
+		return ENDPOINT_OPTIONAL_PARAMETER_ANNOTATION;
 	}
 
 	protected String endpointAccessEnum() {
@@ -194,8 +194,8 @@ public class ConfigurationMetadataAnnotationProcessor extends AbstractProcessor
 		this.metadataEnv = new MetadataGenerationEnvironment(env, configurationPropertiesAnnotation(),
 				configurationPropertiesSourceAnnotation(), nestedConfigurationPropertyAnnotation(),
 				deprecatedConfigurationPropertyAnnotation(), constructorBindingAnnotation(), autowiredAnnotation(),
-				defaultValueAnnotation(), endpointAnnotations(), readOperationAnnotation(),
+				defaultValueAnnotation(), endpointAnnotations(), endpointReadOperationAnnotation(),
-				optionalParameterAnnotation(), nameAnnotation());
+				endpointOptionalParameterAnnotation(), nameAnnotation());
 	}
 
 	@Override
@@ -271,8 +271,7 @@ public class ConfigurationMetadataAnnotationProcessor extends AbstractProcessor
 	}
 
 	private void processExecutableElement(String prefix, ExecutableElement element, Deque<TypeElement> seen) {
-		if ((!element.getModifiers().contains(Modifier.PRIVATE))
+		if ((!element.getModifiers().contains(Modifier.PRIVATE)) && returnsVoid(element)) {
-				&& (TypeKind.VOID != element.getReturnType().getKind())) {
 			Element returns = this.processingEnv.getTypeUtils().asElement(element.getReturnType());
 			if (returns instanceof TypeElement typeElement) {
 				ItemMetadata group = ItemMetadata.newGroup(prefix,
@@ -354,7 +353,7 @@ public class ConfigurationMetadataAnnotationProcessor extends AbstractProcessor
 				"Permitted level of access for the %s endpoint.".formatted(endpointId), defaultAccess, null);
 		this.metadataCollector.add(accessProperty,
 				(existing) -> checkDefaultAccessValueMatchesExisting(existing, defaultAccess, type));
-		if (hasMainReadOperation(element)) {
+		if (isCachableEndpoint(element)) {
 			this.metadataCollector.addIfAbsent(ItemMetadata.newProperty(endpointKey, "cache.time-to-live",
 					Duration.class.getName(), type, null, "Maximum time that a response can be cached.", "0ms", null));
 		}
@@ -371,28 +370,27 @@ public class ConfigurationMetadataAnnotationProcessor extends AbstractProcessor
 		}
 	}
 
-	private boolean hasMainReadOperation(TypeElement element) {
+	private boolean isCachableEndpoint(TypeElement element) {
 		for (ExecutableElement method : ElementFilter.methodsIn(element.getEnclosedElements())) {
-			if (this.metadataEnv.getReadOperationAnnotation(method) != null
+			if (this.metadataEnv.isEndpointReadOperation(method) && returnsVoid(method)
-					&& (TypeKind.VOID != method.getReturnType().getKind()) && hasNoOrOptionalParameters(method)) {
+					&& !hasMandatoryEndpointParameter(method)) {
 				return true;
 			}
 		}
 		return false;
 	}
 
-	private boolean hasNoOrOptionalParameters(ExecutableElement method) {
+	private boolean returnsVoid(ExecutableElement method) {
+		return TypeKind.VOID != method.getReturnType().getKind();
+	}
+
+	private boolean hasMandatoryEndpointParameter(ExecutableElement method) {
 		for (VariableElement parameter : method.getParameters()) {
-			if (!isOptionalParameter(parameter)) {
+			if (!this.metadataEnv.hasEndpointOptionalParameterAnnotation(parameter)) {
-				return false;
+				return true;
 			}
 		}
-		return true;
+		return false;
-	}
-
-	private boolean isOptionalParameter(VariableElement parameter) {
-		return this.metadataEnv.hasNullableAnnotation(parameter)
-				|| this.metadataEnv.hasOptionalParameterAnnotation(parameter);
 	}
 
 	private String getPrefix(AnnotationMirror annotation) {

configuration-metadata/spring-boot-configuration-processor/src/main/java/org/springframework/boot/configurationprocessor/MetadataGenerationEnvironment.java

@@ -96,9 +96,9 @@ class MetadataGenerationEnvironment {
 
 	private final Set<String> endpointAnnotations;
 
-	private final String readOperationAnnotation;
+	private final String endpointReadOperationAnnotation;
 
-	private final String optionalParameterAnnotation;
+	private final String endpointOptionalParameterAnnotation;
 
 	private final String nameAnnotation;
 
@@ -108,7 +108,7 @@ class MetadataGenerationEnvironment {
 			String configurationPropertiesSourceAnnotation, String nestedConfigurationPropertyAnnotation,
 			String deprecatedConfigurationPropertyAnnotation, String constructorBindingAnnotation,
 			String autowiredAnnotation, String defaultValueAnnotation, Set<String> endpointAnnotations,
-			String readOperationAnnotation, String optionalParameterAnnotation, String nameAnnotation) {
+			String endpointReadOperationAnnotation, String endpointOptionalParameterAnnotation, String nameAnnotation) {
 		this.typeUtils = new TypeUtils(environment);
 		this.elements = environment.getElementUtils();
 		this.messager = environment.getMessager();
@@ -122,8 +122,8 @@ class MetadataGenerationEnvironment {
 		this.autowiredAnnotation = autowiredAnnotation;
 		this.defaultValueAnnotation = defaultValueAnnotation;
 		this.endpointAnnotations = endpointAnnotations;
-		this.readOperationAnnotation = readOperationAnnotation;
+		this.endpointReadOperationAnnotation = endpointReadOperationAnnotation;
-		this.optionalParameterAnnotation = optionalParameterAnnotation;
+		this.endpointOptionalParameterAnnotation = endpointOptionalParameterAnnotation;
 		this.nameAnnotation = nameAnnotation;
 	}
 
@@ -370,8 +370,8 @@ class MetadataGenerationEnvironment {
 			.collect(Collectors.toSet());
 	}
 
-	AnnotationMirror getReadOperationAnnotation(Element element) {
+	boolean isEndpointReadOperation(Element element) {
-		return getAnnotation(element, this.readOperationAnnotation);
+		return getAnnotation(element, this.endpointReadOperationAnnotation) != null;
 	}
 
 	AnnotationMirror getNameAnnotation(Element element) {
@@ -382,8 +382,8 @@ class MetadataGenerationEnvironment {
 		return getTypeUseAnnotation(element, NULLABLE_ANNOTATION) != null;
 	}
 
-	boolean hasOptionalParameterAnnotation(Element element) {
+	boolean hasEndpointOptionalParameterAnnotation(Element element) {
-		return getAnnotation(element, this.optionalParameterAnnotation) != null;
+		return getAnnotation(element, this.endpointOptionalParameterAnnotation) != null;
 	}
 
 	private boolean isElementDeprecated(Element element) {

configuration-metadata/spring-boot-configuration-processor/src/test/java/org/springframework/boot/configurationprocessor/EndpointMetadataGenerationTests.java

@@ -28,7 +28,6 @@ import org.springframework.boot.configurationsample.endpoint.CamelCaseEndpoint;
 import org.springframework.boot.configurationsample.endpoint.CustomPropertiesEndpoint;
 import org.springframework.boot.configurationsample.endpoint.EnabledEndpoint;
 import org.springframework.boot.configurationsample.endpoint.NoAccessEndpoint;
-import org.springframework.boot.configurationsample.endpoint.NullableParameterEndpoint;
 import org.springframework.boot.configurationsample.endpoint.OptionalParameterEndpoint;
 import org.springframework.boot.configurationsample.endpoint.ReadOnlyAccessEndpoint;
 import org.springframework.boot.configurationsample.endpoint.SimpleEndpoint;
@@ -195,16 +194,6 @@ class EndpointMetadataGenerationTests extends AbstractMetadataGenerationTests {
 					"Existing property 'management.endpoint.simple.access' from type org.springframework.boot.configurationsample.endpoint.SimpleEndpoint has a conflicting value. Existing value: unrestricted, new value from type org.springframework.boot.configurationsample.endpoint.SimpleEndpoint3: none");
 	}
 
-	@Test
-	void endpointWithNullableParameter() {
-		ConfigurationMetadata metadata = compile(NullableParameterEndpoint.class);
-		assertThat(metadata)
-			.has(Metadata.withGroup("management.endpoint.nullable").fromSource(NullableParameterEndpoint.class));
-		assertThat(metadata).has(access("nullable", Access.UNRESTRICTED));
-		assertThat(metadata).has(cacheTtl("nullable"));
-		assertThat(metadata.getItems()).hasSize(3);
-	}
-
 	@Test
 	void endpointWithOptionalParameter() {
 		ConfigurationMetadata metadata = compile(OptionalParameterEndpoint.class);

configuration-metadata/spring-boot-configuration-processor/src/test/java/org/springframework/boot/configurationprocessor/test/TestConfigurationMetadataAnnotationProcessor.java

@@ -126,12 +126,12 @@ public class TestConfigurationMetadataAnnotationProcessor extends ConfigurationM
 	}
 
 	@Override
-	protected String readOperationAnnotation() {
+	protected String endpointReadOperationAnnotation() {
 		return READ_OPERATION_ANNOTATION;
 	}
 
 	@Override
-	protected String optionalParameterAnnotation() {
+	protected String endpointOptionalParameterAnnotation() {
 		return OPTIONAL_PARAMETER_ANNOTATION;
 	}
 

configuration-metadata/spring-boot-configuration-processor/src/test/java/org/springframework/boot/configurationsample/endpoint/NullableParameterEndpoint.java

@@ -1,37 +0,0 @@
-/*
- * Copyright 2012-present 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.configurationsample.endpoint;
-
-import org.jspecify.annotations.Nullable;
-
-import org.springframework.boot.configurationsample.Endpoint;
-import org.springframework.boot.configurationsample.ReadOperation;
-
-/**
- * An endpoint that uses {@code Nullable} to signal an optional parameter.
- *
- * @author Wonyong Hwang
- */
-@Endpoint(id = "nullable")
-public class NullableParameterEndpoint {
-
-	@ReadOperation
-	public String invoke(@Nullable String parameter) {
-		return "test with " + parameter;
-	}
-
-}

module/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/endpoint/invoke/reflect/OperationMethod.java

@@ -34,7 +34,7 @@ import org.springframework.util.Assert;
  * @since 2.0.0
  * @see ReflectiveOperationInvoker
  */
-public class OperationMethod {
+public abstract class OperationMethod {
 
 	private static final ParameterNameDiscoverer DEFAULT_PARAMETER_NAME_DISCOVERER = new DefaultParameterNameDiscoverer();
 
@@ -44,18 +44,6 @@ public class OperationMethod {
 
 	private final OperationParameters operationParameters;
 
-	/**
-	 * Create a new {@link OperationMethod} instance.
-	 * @param method the source method
-	 * @param operationType the operation type
-	 * @deprecated since 4.0.0 for removal in 4.2.0 in favor of
-	 * {@link #OperationMethod(Method, OperationType, Predicate)}
-	 */
-	@Deprecated(since = "4.0.0", forRemoval = true)
-	public OperationMethod(Method method, OperationType operationType) {
-		this(method, operationType, (parameter) -> false);
-	}
-
 	/**
 	 * Create a new {@link OperationMethod} instance.
 	 * @param method the source method
@@ -63,7 +51,7 @@ public class OperationMethod {
 	 * @param optionalParameters predicate to test if a parameter is optional
 	 * @since 4.0.0
 	 */
-	public OperationMethod(Method method, OperationType operationType, Predicate<Parameter> optionalParameters) {
+	protected OperationMethod(Method method, OperationType operationType, Predicate<Parameter> optionalParameters) {
 		Assert.notNull(method, "'method' must not be null");
 		Assert.notNull(operationType, "'operationType' must not be null");
 		this.method = method;

module/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/endpoint/invoke/reflect/OperationMethodParameter.java

@@ -21,7 +21,6 @@ import java.lang.reflect.Parameter;
 import java.util.function.Predicate;
 
 import org.springframework.boot.actuate.endpoint.invoke.OperationParameter;
-import org.springframework.core.Nullness;
 
 /**
  * {@link OperationParameter} created from an {@link OperationMethod}.
@@ -61,11 +60,7 @@ class OperationMethodParameter implements OperationParameter {
 
 	@Override
 	public boolean isMandatory() {
-		return !isOptional();
+		return !this.optional.test(this.parameter);
-	}
-
-	private boolean isOptional() {
-		return Nullness.NULLABLE == Nullness.forParameter(this.parameter) || this.optional.test(this.parameter);
 	}
 
 	@Override

module/spring-boot-actuator/src/test/java/org/springframework/boot/actuate/endpoint/invoke/reflect/OperationMethodParameterTests.java

@@ -43,12 +43,6 @@ class OperationMethodParameterTests {
 
 	private final Method example = ReflectionUtils.findMethod(getClass(), "example", String.class, String.class);
 
-	private final Method exampleJSpecifyNullable = ReflectionUtils.findMethod(getClass(), "exampleJSpecifyNullable",
-			String.class, String.class);
-
-	private final Method exampleSpringNullable = ReflectionUtils.findMethod(getClass(), "exampleSpringNullable",
-			String.class, String.class);
-
 	private Method exampleAnnotation = ReflectionUtils.findMethod(getClass(), "exampleAnnotation", String.class);
 
 	@Test
@@ -79,20 +73,6 @@ class OperationMethodParameterTests {
 		assertThat(parameter.isMandatory()).isFalse();
 	}
 
-	@Test
-	void isMandatoryWhenJSpecifyNullableAnnotationShouldReturnFalse() {
-		OperationMethodParameter parameter = new OperationMethodParameter("name",
-				this.exampleJSpecifyNullable.getParameters()[1], this::isOptionalParameter);
-		assertThat(parameter.isMandatory()).isFalse();
-	}
-
-	@Test
-	void isMandatoryWhenSpringNullableAnnotationShouldReturnFalse() {
-		OperationMethodParameter parameter = new OperationMethodParameter("name",
-				this.exampleSpringNullable.getParameters()[1], this::isOptionalParameter);
-		assertThat(parameter.isMandatory()).isFalse();
-	}
-
 	@Test
 	void getAnnotationShouldReturnAnnotation() {
 		OperationMethodParameter parameter = new OperationMethodParameter("name",
@@ -109,13 +89,6 @@ class OperationMethodParameterTests {
 	void example(String one, @TestOptional String two) {
 	}
 
-	void exampleJSpecifyNullable(String one, @org.jspecify.annotations.Nullable String two) {
-	}
-
-	@SuppressWarnings("deprecation")
-	void exampleSpringNullable(String one, @org.springframework.lang.Nullable String two) {
-	}
-
 	void exampleAnnotation(@Selector(match = Match.ALL_REMAINING) String allRemaining) {
 	}
 

module/spring-boot-actuator/src/test/java/org/springframework/boot/actuate/endpoint/invoke/reflect/OperationMethodTests.java

@@ -17,8 +17,6 @@
 package org.springframework.boot.actuate.endpoint.invoke.reflect;
 
 import java.lang.reflect.Method;
-import java.lang.reflect.Parameter;
-import java.util.function.Predicate;
 
 import org.junit.jupiter.api.Test;
 
@@ -36,39 +34,35 @@ import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException
  */
 class OperationMethodTests {
 
-	private static final Predicate<Parameter> NON_OPTIONAL = (parameter) -> false;
-
 	private final Method exampleMethod = ReflectionUtils.findMethod(getClass(), "example", String.class);
 
 	@Test
 	void createWhenMethodIsNullShouldThrowException() {
-		assertThatIllegalArgumentException()
+		assertThatIllegalArgumentException().isThrownBy(() -> new TestOperationMethod(null, OperationType.READ))
-			.isThrownBy(() -> new OperationMethod(null, OperationType.READ, NON_OPTIONAL))
 			.withMessageContaining("'method' must not be null");
 	}
 
 	@Test
 	void createWhenOperationTypeIsNullShouldThrowException() {
-		assertThatIllegalArgumentException()
+		assertThatIllegalArgumentException().isThrownBy(() -> new TestOperationMethod(this.exampleMethod, null))
-			.isThrownBy(() -> new OperationMethod(this.exampleMethod, null, NON_OPTIONAL))
 			.withMessageContaining("'operationType' must not be null");
 	}
 
 	@Test
 	void getMethodShouldReturnMethod() {
-		OperationMethod operationMethod = new OperationMethod(this.exampleMethod, OperationType.READ, NON_OPTIONAL);
+		OperationMethod operationMethod = new TestOperationMethod(this.exampleMethod, OperationType.READ);
 		assertThat(operationMethod.getMethod()).isEqualTo(this.exampleMethod);
 	}
 
 	@Test
 	void getOperationTypeShouldReturnOperationType() {
-		OperationMethod operationMethod = new OperationMethod(this.exampleMethod, OperationType.READ, NON_OPTIONAL);
+		OperationMethod operationMethod = new TestOperationMethod(this.exampleMethod, OperationType.READ);
 		assertThat(operationMethod.getOperationType()).isEqualTo(OperationType.READ);
 	}
 
 	@Test
 	void getParametersShouldReturnParameters() {
-		OperationMethod operationMethod = new OperationMethod(this.exampleMethod, OperationType.READ, NON_OPTIONAL);
+		OperationMethod operationMethod = new TestOperationMethod(this.exampleMethod, OperationType.READ);
 		OperationParameters parameters = operationMethod.getParameters();
 		assertThat(parameters.getParameterCount()).isOne();
 		assertThat(parameters.iterator().next().getName()).isEqualTo("name");

module/spring-boot-actuator/src/test/java/org/springframework/boot/actuate/endpoint/invoke/reflect/ReflectiveOperationInvokerTests.java

@@ -57,7 +57,7 @@ class ReflectiveOperationInvokerTests {
 	@BeforeEach
 	void setup() {
 		this.target = new Example();
-		this.operationMethod = new OperationMethod(ReflectionUtils.findMethod(Example.class, "reverse",
+		this.operationMethod = new TestOperationMethod(ReflectionUtils.findMethod(Example.class, "reverse",
 				ApiVersion.class, SecurityContext.class, String.class), OperationType.READ, this::isOptional);
 		this.parameterValueMapper = (parameter, value) -> (value != null) ? value.toString() : null;
 	}
@@ -102,7 +102,7 @@ class ReflectiveOperationInvokerTests {
 
 	@Test
 	void invokeWhenMissingOptionalArgumentShouldInvoke() {
-		OperationMethod operationMethod = new OperationMethod(ReflectionUtils.findMethod(Example.class,
+		OperationMethod operationMethod = new TestOperationMethod(ReflectionUtils.findMethod(Example.class,
 				"reverseOptional", ApiVersion.class, SecurityContext.class, String.class), OperationType.READ,
 				this::isOptional);
 		ReflectiveOperationInvoker invoker = new ReflectiveOperationInvoker(this.target, operationMethod,

module/spring-boot-actuator/src/test/java/org/springframework/boot/actuate/endpoint/invoke/reflect/TestOperationMethod.java

@@ -0,0 +1,42 @@
+/*
+ * Copyright 2012-present 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.actuate.endpoint.invoke.reflect;
+
+import java.lang.reflect.Method;
+import java.lang.reflect.Parameter;
+import java.util.function.Predicate;
+
+import org.springframework.boot.actuate.endpoint.OperationType;
+
+/**
+ * Test {@link OperationMethod}.
+ *
+ * @author Phillip Webb
+ */
+public class TestOperationMethod extends OperationMethod {
+
+	public static final Predicate<Parameter> NON_OPTIONAL = (parameter) -> false;
+
+	public TestOperationMethod(Method method, OperationType operationType) {
+		this(method, operationType, NON_OPTIONAL);
+	}
+
+	public TestOperationMethod(Method method, OperationType operationType, Predicate<Parameter> optionalParameters) {
+		super(method, operationType, optionalParameters);
+	}
+
+}

module/spring-boot-actuator/src/test/java/org/springframework/boot/actuate/endpoint/invoker/cache/CachingOperationInvokerAdvisorTests.java

@@ -37,6 +37,7 @@ import org.springframework.boot.actuate.endpoint.SecurityContext;
 import org.springframework.boot.actuate.endpoint.invoke.OperationInvoker;
 import org.springframework.boot.actuate.endpoint.invoke.OperationParameters;
 import org.springframework.boot.actuate.endpoint.invoke.reflect.OperationMethod;
+import org.springframework.boot.actuate.endpoint.invoke.reflect.TestOperationMethod;
 import org.springframework.boot.actuate.endpoint.web.WebServerNamespace;
 import org.springframework.core.annotation.MergedAnnotations;
 import org.springframework.util.ReflectionUtils;
@@ -163,7 +164,7 @@ class CachingOperationInvokerAdvisorTests {
 
 	private OperationMethod getOperationMethod(String methodName, Class<?>... parameterTypes) {
 		Method method = ReflectionUtils.findMethod(TestOperations.class, methodName, parameterTypes);
-		return new OperationMethod(method, OperationType.READ,
+		return new TestOperationMethod(method, OperationType.READ,
 				(parameter) -> MergedAnnotations.from(parameter).isPresent(TestOptional.class));
 	}