Open parts of AOT api for extensibility.

Make method generation context available for subclassing which allows dedicated tests to be implemented in store modules without having to bootstrap the entire AOT facility. This also demanded to change visibility of fragment metadata.

Along the way fixed json rendering of method metadata by wrapping nested values in json objects. This allows to print out values of eg. list type as json array.

Added test to cover json repository metadata rendering and storage.

See: #3265

Author: christophstrobl

src/main/java/org/springframework/data/repository/aot/generate/AotQueryMethodGenerationContext.java

@@ -50,7 +50,7 @@ public class AotQueryMethodGenerationContext {
 	private final MethodMetadata targetMethodMetadata;
 	private final VariableNameFactory variableNameFactory;
 
-	AotQueryMethodGenerationContext(RepositoryInformation repositoryInformation, Method method, QueryMethod queryMethod,
+	protected AotQueryMethodGenerationContext(RepositoryInformation repositoryInformation, Method method, QueryMethod queryMethod,
 			AotRepositoryFragmentMetadata targetTypeMetadata) {
 
 		this.method = method;

src/main/java/org/springframework/data/repository/aot/generate/AotRepositoryFragmentMetadata.java

@@ -35,7 +35,7 @@
  * @author Mark Paluch
  * @since 4.0
  */
-class AotRepositoryFragmentMetadata {
+public class AotRepositoryFragmentMetadata {
 
 	private final ClassName className;
 	private final Map<String, FieldSpec> fields = new HashMap<>(3);

src/main/java/org/springframework/data/repository/aot/generate/AotRepositoryMethod.java

@@ -54,7 +54,7 @@ static JSONObject queryMetadataToJson(QueryMetadata queryMetadata) throws JSONEx
 		JSONObject query = new JSONObject();
 
 		for (Map.Entry<String, Object> entry : queryMetadata.serialize().entrySet()) {
-			query.put(entry.getKey(), entry.getValue());
+			query.put(entry.getKey(), JSONObject.wrap(entry.getValue()));
 		}
 
 		return query;

src/test/java/org/springframework/data/repository/aot/generate/RepositoryContributorUnitTests.java

@@ -24,13 +24,14 @@
 import example.UserRepositoryExtensionImpl;
 
 import java.lang.reflect.Method;
+import java.lang.reflect.Parameter;
+import java.util.Arrays;
 import java.util.Map;
 import java.util.Optional;
 import java.util.Set;
 
 import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.Test;
-
 import org.springframework.aot.test.generate.TestGenerationContext;
 import org.springframework.core.test.tools.TestCompiler;
 import org.springframework.data.aot.CodeContributionAssert;
@@ -95,6 +96,53 @@ public Map<String, Object> serialize() {
 		new CodeContributionAssert(generationContext).contributesReflectionFor(expectedTypeName);
 	}
 
+	@Test // GH-3265
+	void writesCapturedQueryMetadataToResources() {
+
+		DummyModuleAotRepositoryContext aotContext = new DummyModuleAotRepositoryContext(UserRepository.class, null);
+		RepositoryContributor repositoryContributor = new RepositoryContributor(aotContext) {
+
+			@Override
+			protected @Nullable MethodContributor<? extends QueryMethod> contributeQueryMethod(Method method) {
+
+				return MethodContributor
+						.forQueryMethod(
+								new QueryMethod(method, getRepositoryInformation(), getProjectionFactory(), DefaultParameters::new))
+						.withMetadata(new QueryMetadata() {
+
+							@Override
+							public Map<String, Object> serialize() {
+
+								return Map.of("filter", "FILTER(%s > $1)".formatted(method.getName()), "project",
+										Arrays.stream(method.getParameters()).map(Parameter::getName).toList());
+							}
+						}).contribute(context -> {
+
+							CodeBlock.Builder builder = CodeBlock.builder();
+							if (!ClassUtils.isVoidType(method.getReturnType())) {
+								builder.addStatement("return null");
+							}
+
+							return builder.build();
+						});
+			}
+		};
+
+		TestGenerationContext generationContext = new TestGenerationContext(UserRepository.class);
+		repositoryContributor.contribute(generationContext);
+		generationContext.writeGeneratedContent();
+
+		String expectedTypeName = "example.UserRepositoryImpl__Aot";
+
+		TestCompiler.forSystem().with(generationContext).compile(compiled -> {
+			String content = compiled.getResourceFile().getContent();
+			assertThat(content).containsIgnoringWhitespaces("\"filter\": \"FILTER(doSomething > $1)\"")
+					.containsIgnoringWhitespaces("\"project\": [\n\"firstname\"\n]");
+		});
+
+		new CodeContributionAssert(generationContext).contributesReflectionFor(expectedTypeName);
+	}
+
 	@Test // GH-3279
 	void callsMethodContributionForQueryMethod() {
 

src/test/java/org/springframework/data/repository/aot/generate/StubRepositoryInformation.java

@@ -108,7 +108,7 @@ public boolean isCustomMethod(Method method) {
 
 	@Override
 	public boolean isQueryMethod(Method method) {
-		return false;
+		return !isBaseClassMethod(method);
 	}
 
 	@Override