feat(mcp): Refactor MCP server API to use Specification pattern

- Rename Registration classes to Specification (SyncToolRegistration → SyncToolSpecification)
- Update transport classes to use Provider suffix (WebFluxSseServerTransport → WebFluxSseServerTransportProvider)
- Add exchange parameter to handler methods for better context passing
- Introduce McpBackwardCompatibility class to maintain backward compatibility
- Update MCP Server documentation to reflect new API patterns
- Add tests for backward compatibility

The changes align with the MCP specification evolution while maintaining backward compatibility through deprecated APIs.

Signed-off-by: Christian Tzolov <[email protected]>

Author: tzolov

auto-configurations/spring-ai-mcp-server/src/main/java/org/springframework/ai/autoconfigure/mcp/server/McpBackwardCompatibility.java

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+/*
+* 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.autoconfigure.mcp.server;
+
+import java.util.List;
+import java.util.function.BiConsumer;
+import java.util.function.Consumer;
+import java.util.stream.Collectors;
+
+import io.modelcontextprotocol.server.McpServerFeatures;
+import io.modelcontextprotocol.server.McpSyncServerExchange;
+import io.modelcontextprotocol.spec.McpSchema;
+
+import org.springframework.beans.factory.ObjectProvider;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.util.CollectionUtils;
+
+/**
+ * @author Christian Tzolov
+ */
+@Deprecated
+@Configuration
+public class McpBackwardCompatibility {
+
+	@Bean
+	public List<BiConsumer<McpSyncServerExchange, List<McpSchema.Root>>> syncRootsChangeConsumerToHandler(
+			List<Consumer<List<McpSchema.Root>>> rootsChangeConsumers) {
+
+		if (CollectionUtils.isEmpty(rootsChangeConsumers)) {
+			return List.of();
+		}
+
+		return rootsChangeConsumers.stream().map(c -> new BiConsumer<McpSyncServerExchange, List<McpSchema.Root>>() {
+			@Override
+			public void accept(McpSyncServerExchange exchange, List<McpSchema.Root> roots) {
+				c.accept(roots);
+			}
+		}).collect(Collectors.toList());
+	}
+
+	@Bean
+	public List<McpServerFeatures.SyncToolSpecification> syncToolsRegistrationToSpecificaiton(
+			ObjectProvider<List<McpServerFeatures.SyncToolRegistration>> toolRegistrations) {
+
+		return toolRegistrations.stream()
+			.flatMap(List::stream)
+			.map(McpServerFeatures.SyncToolRegistration::toSpecification)
+			.toList();
+	}
+
+	@Bean
+	public List<McpServerFeatures.SyncResourceSpecification> syncResourceRegistrationToSpecificaiton(
+			ObjectProvider<List<McpServerFeatures.SyncResourceRegistration>> resourceRegistrations) {
+
+		return resourceRegistrations.stream()
+			.flatMap(List::stream)
+			.map(McpServerFeatures.SyncResourceRegistration::toSpecification)
+			.toList();
+	}
+
+	@Bean
+	public List<McpServerFeatures.SyncPromptSpecification> syncPromptRegistrationToSpecificaiton(
+			ObjectProvider<List<McpServerFeatures.SyncPromptRegistration>> promptRegistrations) {
+
+		return promptRegistrations.stream()
+			.flatMap(List::stream)
+			.map(McpServerFeatures.SyncPromptRegistration::toSpecification)
+			.toList();
+	}
+
+	// Async
+	@Bean
+	public List<McpServerFeatures.AsyncToolSpecification> asyncToolsRegistrationToSpecificaiton(
+			ObjectProvider<List<McpServerFeatures.AsyncToolRegistration>> toolRegistrations) {
+
+		return toolRegistrations.stream()
+			.flatMap(List::stream)
+			.map(McpServerFeatures.AsyncToolRegistration::toSpecification)
+			.toList();
+	}
+
+	@Bean
+	public List<McpServerFeatures.AsyncResourceSpecification> asyncResourceRegistrationToSpecificaiton(
+			ObjectProvider<List<McpServerFeatures.AsyncResourceRegistration>> resourceRegistrations) {
+
+		return resourceRegistrations.stream()
+			.flatMap(List::stream)
+			.map(McpServerFeatures.AsyncResourceRegistration::toSpecification)
+			.toList();
+	}
+
+	@Bean
+	public List<McpServerFeatures.AsyncPromptSpecification> asyncPromptRegistrationToSpecificaiton(
+			ObjectProvider<List<McpServerFeatures.AsyncPromptRegistration>> promptRegistrations) {
+
+		return promptRegistrations.stream()
+			.flatMap(List::stream)
+			.map(McpServerFeatures.AsyncPromptRegistration::toSpecification)
+			.toList();
+	}
+
+}