GH-2633: MCP client autoconfiguration runtime hints (#2683)

Fixes: https://github.com/spring-projects/spring-ai/issues/2633

- Create McpClientAutoConfigurationRuntimeHints class
- Implement registerHints method to support JSON resources
- Add test class with comprehensive assertions
- Update aot.factories to register the new runtime hints
- Add sample JSON configuration files for testing

Signed-off-by: Soby Chacko <soby.chacko@broadcom.com>

auto-configurations/mcp/spring-ai-autoconfigure-mcp-client/src/main/java/org/springframework/ai/mcp/client/autoconfigure/aot/McpClientAutoConfigurationRuntimeHints.java

@@ -0,0 +1,41 @@
+/*
+ * Copyright 2025-2025 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.ai.mcp.client.autoconfigure.aot;
+
+import org.springframework.aot.hint.MemberCategory;
+import org.springframework.aot.hint.RuntimeHints;
+import org.springframework.aot.hint.RuntimeHintsRegistrar;
+
+import static org.springframework.ai.aot.AiRuntimeHints.findJsonAnnotatedClassesInPackage;
+
+/**
+ * @author Josh Long
+ * @author Soby Chacko
+ */
+public class McpClientAutoConfigurationRuntimeHints implements RuntimeHintsRegistrar {
+
+	@Override
+	public void registerHints(RuntimeHints hints, ClassLoader classLoader) {
+		hints.resources().registerPattern("**.json");
+
+		var mcs = MemberCategory.values();
+		for (var tr : findJsonAnnotatedClassesInPackage("org.springframework.ai.mcp.client.autoconfigure")) {
+			hints.reflection().registerType(tr, mcs);
+		}
+	}
+
+}

auto-configurations/mcp/spring-ai-autoconfigure-mcp-client/src/main/resources/META-INF/spring/aot.factories

@@ -0,0 +1,2 @@
+org.springframework.aot.hint.RuntimeHintsRegistrar=\
+	org.springframework.ai.mcp.client.autoconfigure.aot.McpClientAutoConfigurationRuntimeHints

auto-configurations/mcp/spring-ai-autoconfigure-mcp-client/src/test/java/org/springframework/ai/mcp/client/autoconfigure/McpClientAutoConfigurationRuntimeHintsTests.java

@@ -0,0 +1,100 @@
+/*
+ * Copyright 2025-2025 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.ai.mcp.client.autoconfigure;
+
+import java.io.IOException;
+import java.util.HashSet;
+import java.util.Set;
+
+import org.junit.jupiter.api.Test;
+
+import org.springframework.ai.mcp.client.autoconfigure.aot.McpClientAutoConfigurationRuntimeHints;
+import org.springframework.ai.mcp.client.autoconfigure.properties.McpStdioClientProperties;
+import org.springframework.aot.hint.RuntimeHints;
+import org.springframework.aot.hint.TypeReference;
+import org.springframework.core.io.Resource;
+import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
+
+import static org.assertj.core.api.AssertionsForClassTypes.assertThat;
+import static org.springframework.ai.aot.AiRuntimeHints.findJsonAnnotatedClassesInPackage;
+
+/**
+ * @author Soby Chacko
+ */
+public class McpClientAutoConfigurationRuntimeHintsTests {
+
+	@Test
+	void registerHints() throws IOException {
+
+		RuntimeHints runtimeHints = new RuntimeHints();
+
+		McpClientAutoConfigurationRuntimeHints mcpRuntimeHints = new McpClientAutoConfigurationRuntimeHints();
+		mcpRuntimeHints.registerHints(runtimeHints, null);
+
+		boolean hasJsonPattern = runtimeHints.resources()
+			.resourcePatternHints()
+			.anyMatch(resourceHints -> resourceHints.getIncludes()
+				.stream()
+				.anyMatch(pattern -> "**.json".equals(pattern.getPattern())));
+
+		assertThat(hasJsonPattern).as("The **.json resource pattern should be registered").isTrue();
+
+		PathMatchingResourcePatternResolver resolver = new PathMatchingResourcePatternResolver();
+		Resource[] resources = resolver.getResources("classpath*:**/*.json");
+
+		assertThat(resources.length).isGreaterThan(1);
+
+		boolean foundRootJson = false;
+		boolean foundSubfolderJson = false;
+
+		for (Resource resource : resources) {
+			try {
+				String path = resource.getURL().getPath();
+				if (path.endsWith("/test-config.json")) {
+					foundRootJson = true;
+				}
+				else if (path.endsWith("/nested/nested-config.json")) {
+					foundSubfolderJson = true;
+				}
+			}
+			catch (IOException e) {
+				// nothing to do
+			}
+		}
+
+		assertThat(foundRootJson).as("test-config.json should exist in the root test resources directory").isTrue();
+
+		assertThat(foundSubfolderJson).as("nested-config.json should exist in the nested subfolder").isTrue();
+
+		Set<TypeReference> jsonAnnotatedClasses = findJsonAnnotatedClassesInPackage(
+				"org.springframework.ai.mcp.client.autoconfigure");
+
+		Set<TypeReference> registeredTypes = new HashSet<>();
+		runtimeHints.reflection().typeHints().forEach(typeHint -> registeredTypes.add(typeHint.getType()));
+
+		for (TypeReference jsonAnnotatedClass : jsonAnnotatedClasses) {
+			assertThat(registeredTypes.contains(jsonAnnotatedClass))
+				.as("JSON-annotated class %s should be registered for reflection", jsonAnnotatedClass.getName())
+				.isTrue();
+		}
+
+		assertThat(registeredTypes.contains(TypeReference.of(McpStdioClientProperties.Parameters.class)))
+			.as("McpStdioClientProperties.Parameters class should be registered")
+			.isTrue();
+	}
+
+}

auto-configurations/mcp/spring-ai-autoconfigure-mcp-client/src/test/resources/nested/nested-config.json

@@ -0,0 +1,8 @@
+{
+  "name": "nested-config",
+  "description": "Test JSON file in nested subfolder of test resources",
+  "version": "1.0.0",
+  "nestedProperties": {
+	"nestedProperty1": "nestedValue1"
+  }
+}

auto-configurations/mcp/spring-ai-autoconfigure-mcp-client/src/test/resources/test-config.json

@@ -0,0 +1,8 @@
+{
+  "name": "test-config",
+  "description": "Test JSON file in root test resources folder",
+  "version": "1.0.0",
+  "properties": {
+	"testProperty1": "value1"
+  }
+}