Polish "Support additional nullness signal for Actuator endpoints"

See gh-46854

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

@@ -52,13 +52,10 @@ import org.springframework.boot.configurationprocessor.metadata.ItemDeprecation;
  * @author Stephane Nicoll
  * @author Scott Frederick
  * @author Moritz Halbritter
- * @author Wonyong Hwang
  */
 class MetadataGenerationEnvironment {
 
-	private static final Set<String> NULLABLE_ANNOTATIONS = Set.of(
-			"org.springframework.lang.Nullable",
-			"org.jspecify.annotations.Nullable");
+	private static final String NULLABLE_ANNOTATION = "org.jspecify.annotations.Nullable";
 
 	private static final Set<String> TYPE_EXCLUDES = Set.of("com.zaxxer.hikari.IConnectionCustomizer",
 			"groovy.lang.MetaClass", "groovy.text.markup.MarkupTemplateEngine", "java.io.Writer", "java.io.PrintWriter",
@@ -268,7 +265,12 @@ class MetadataGenerationEnvironment {
 					return annotation;
 				}
 			}
+		}
+		return null;
+	}
 
+	private AnnotationMirror getTypeUseAnnotation(Element element, String type) {
+		if (element != null) {
 			for (AnnotationMirror annotation : element.asType().getAnnotationMirrors()) {
 				if (type.equals(annotation.getAnnotationType().toString())) {
 					return annotation;
@@ -377,12 +379,7 @@ class MetadataGenerationEnvironment {
 	}
 
 	boolean hasNullableAnnotation(Element element) {
-		for (String nullableAnnotation : NULLABLE_ANNOTATIONS) {
-			if (getAnnotation(element, nullableAnnotation) != null) {
-				return true;
-			}
-		}
-		return false;
+		return getTypeUseAnnotation(element, NULLABLE_ANNOTATION) != null;
 	}
 
 	boolean hasOptionalParameterAnnotation(Element element) {

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

@@ -28,6 +28,8 @@ 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;
 import org.springframework.boot.configurationsample.endpoint.SimpleEndpoint2;
@@ -35,8 +37,6 @@ import org.springframework.boot.configurationsample.endpoint.SimpleEndpoint3;
 import org.springframework.boot.configurationsample.endpoint.SpecificEndpoint;
 import org.springframework.boot.configurationsample.endpoint.UnrestrictedAccessEndpoint;
 import org.springframework.boot.configurationsample.endpoint.incremental.IncrementalEndpoint;
-import org.springframework.boot.configurationsample.endpoint.NullableParameterEndpoint;
-import org.springframework.boot.configurationsample.endpoint.OptionalParameterEndpoint;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatRuntimeException;
@@ -196,37 +196,25 @@ class EndpointMetadataGenerationTests extends AbstractMetadataGenerationTests {
 	}
 
 	@Test
-	void nullableParameterEndpoint() {
+	void endpointWithNullableParameter() {
 		ConfigurationMetadata metadata = compile(NullableParameterEndpoint.class);
-		assertThat(metadata).has(Metadata.withGroup("management.endpoint.nullable").fromSource(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 optionalParameterEndpoint() {
+	void endpointWithOptionalParameter() {
 		ConfigurationMetadata metadata = compile(OptionalParameterEndpoint.class);
-		assertThat(metadata).has(Metadata.withGroup("management.endpoint.optional").fromSource(OptionalParameterEndpoint.class));
+		assertThat(metadata)
+			.has(Metadata.withGroup("management.endpoint.optional").fromSource(OptionalParameterEndpoint.class));
 		assertThat(metadata).has(access("optional", Access.UNRESTRICTED));
 		assertThat(metadata).has(cacheTtl("optional"));
 		assertThat(metadata.getItems()).hasSize(3);
 	}
 
-	@Test
-	void nullableAndOptionalParameterEquivalence() {
-		ConfigurationMetadata nullableMetadata = compile(NullableParameterEndpoint.class);
-		ConfigurationMetadata optionalMetadata = compile(OptionalParameterEndpoint.class);
-
-		assertThat(nullableMetadata.getItems()).hasSize(3);
-		assertThat(optionalMetadata.getItems()).hasSize(3);
-
-		assertThat(nullableMetadata).has(access("nullable", Access.UNRESTRICTED));
-		assertThat(optionalMetadata).has(access("optional", Access.UNRESTRICTED));
-		assertThat(nullableMetadata).has(cacheTtl("nullable"));
-		assertThat(optionalMetadata).has(cacheTtl("optional"));
-	}
-
 	private Metadata.MetadataItemCondition access(String endpointId, Access defaultValue) {
 		return defaultAccess(endpointId, endpointId, defaultValue);
 	}

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

@@ -16,12 +16,13 @@
 
 package org.springframework.boot.configurationsample.endpoint;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.boot.configurationsample.Endpoint;
 import org.springframework.boot.configurationsample.ReadOperation;
-import org.jspecify.annotations.Nullable;
 
 /**
- * An endpoint with @Nullable parameter to test.
+ * An endpoint that uses {@code Nullable} to signal an optional parameter.
  *
  * @author Wonyong Hwang
  */

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

@@ -14,23 +14,23 @@
  * limitations under the License.
  */
 
- package org.springframework.boot.configurationsample.endpoint;
+package org.springframework.boot.configurationsample.endpoint;
 
- import org.springframework.boot.configurationsample.Endpoint;
- import org.springframework.boot.configurationsample.ReadOperation;
- import org.springframework.boot.configurationsample.OptionalParameter;
- 
- /**
-  * An endpoint with @OptionalParameter to compare with @Nullable behavior.
-  *
-  * @author Wonyong Hwang
-  */
- @Endpoint(id = "optional")
- public class OptionalParameterEndpoint {
- 
-     @ReadOperation
-     public String invoke(@OptionalParameter String parameter) {
-         return "test with " + parameter;
-     }
- 
- }
+import org.springframework.boot.configurationsample.Endpoint;
+import org.springframework.boot.configurationsample.OptionalParameter;
+import org.springframework.boot.configurationsample.ReadOperation;
+
+/**
+ * An endpoint that uses {@code OptionalParameter} to signal an optional parameter.
+ *
+ * @author Wonyong Hwang
+ */
+@Endpoint(id = "optional")
+public class OptionalParameterEndpoint {
+
+	@ReadOperation
+	public String invoke(@OptionalParameter String parameter) {
+		return "test with " + parameter;
+	}
+
+}