Adjustments to fix the test

src/main/java/spring/ai/mcp/client/McpAsyncSession.java

@@ -11,12 +11,14 @@ import reactor.core.publisher.Mono;
 import reactor.core.publisher.MonoSink;
 import spring.ai.mcp.spec.McpAsyncTransport;
 import spring.ai.mcp.spec.McpTransport;
+
+import org.springframework.util.Assert;
+
 import spring.ai.mcp.spec.McpSchema;
 
 public class McpAsyncSession {
 
-	private final ConcurrentHashMap<Object, MonoSink<McpSchema.JSONRPCResponse>> pendingResponses
+	private final ConcurrentHashMap<Object, MonoSink<McpSchema.JSONRPCResponse>> pendingResponses = new ConcurrentHashMap<>();
-			= new ConcurrentHashMap<>();
 
 	private final Duration requestTimeout;
 
@@ -24,9 +26,12 @@ public class McpAsyncSession {
 
 	private final McpAsyncTransport transport;
 
-	public McpAsyncSession(Duration requestTimeout,
+	public McpAsyncSession(Duration requestTimeout, ObjectMapper objectMapper, McpAsyncTransport transport) {
-			ObjectMapper objectMapper,
+
-			McpAsyncTransport transport) {
+		Assert.notNull(requestTimeout, "Request timeout must not be null");
+		Assert.notNull(objectMapper, "ObjectMapper must not be null");
+		Assert.notNull(transport, "Transport must not be null");
+
 		this.requestTimeout = requestTimeout;
 		this.objectMapper = objectMapper;
 		this.transport = transport;
@@ -37,7 +42,8 @@ public class McpAsyncSession {
 					var sink = pendingResponses.remove(response.id());
 					if (sink == null) {
 						System.out.println("Unexpected response for unkown id " + response.id());
-					} else {
+					}
+					else {
 						sink.success(response);
 					}
 				}
@@ -60,34 +66,36 @@ public class McpAsyncSession {
 
 		return Mono.<McpSchema.JSONRPCResponse>create(sink -> {
 			this.pendingResponses.put(requestId, sink);
-			McpSchema.JSONRPCRequest jsonrpcRequest = new McpSchema.JSONRPCRequest(McpSchema.JSONRPC_VERSION, method, requestId, requestParams);
+			McpSchema.JSONRPCRequest jsonrpcRequest = new McpSchema.JSONRPCRequest(McpSchema.JSONRPC_VERSION, method,
+					requestId, requestParams);
 			try {
 				// TODO: This is non-blocking, but it's actually a synchronous call,
 				// perhaps there's no need to make it return Mono?
 				this.transport.sendMessage(jsonrpcRequest)
-				              // TODO: It's most efficient to create a dedicated
+					// TODO: It's most efficient to create a dedicated
-				              //  Subscriber here
+					// Subscriber here
-				              .subscribe(v -> {}, e -> {
+					.subscribe(v -> {
-								  this.pendingResponses.remove(requestId);
+					}, e -> {
-								  sink.error(e);
+						this.pendingResponses.remove(requestId);
-				              });
+						sink.error(e);
-			} catch (Exception e) {
+					});
+			}
+			catch (Exception e) {
 				sink.error(e);
 			}
-		})
+		}).timeout(this.requestTimeout).handle((jsonRpcResponse, s) -> {
-		           .timeout(this.requestTimeout)
+			if (jsonRpcResponse.error() != null) {
-		           .handle((jsonRpcResponse, s) -> {
+				s.error(new McpError(jsonRpcResponse.error()));
-					   if (jsonRpcResponse.error() != null) {
+			}
-						   s.error(new McpError(jsonRpcResponse.error()));
+			else {
-					   } else {
+				if (typeRef.getType().getTypeName().equals("java.lang.Void")) {
-						   if (typeRef.getType().getTypeName().equals("java.lang.Void")) {
+					s.complete();
-							   s.complete();
+				}
-						   } else {
+				else {
-							   s.next(this.objectMapper.convertValue(jsonRpcResponse.result(),
+					s.next(this.objectMapper.convertValue(jsonRpcResponse.result(), typeRef));
-									   typeRef));
+				}
-						   }
+			}
-					   }
+		});
-		           });
 	}
 
 	public static class McpError extends RuntimeException {
@@ -95,6 +103,7 @@ public class McpAsyncSession {
 		public McpError(Object error) {
 			super(error.toString());
 		}
+
 	}
 
 	public Mono<Void> sendNotification(String method) {
@@ -102,8 +111,8 @@ public class McpAsyncSession {
 	}
 
 	public Mono<Void> sendNotification(String method, Map<String, Object> params) {
-		McpSchema.JSONRPCNotification
+		McpSchema.JSONRPCNotification jsonrpcNotification = new McpSchema.JSONRPCNotification(McpSchema.JSONRPC_VERSION,
-				jsonrpcNotification = new McpSchema.JSONRPCNotification(McpSchema.JSONRPC_VERSION, method, params);
+				method, params);
 		try {
 			// TODO: make it non-blocking
 			this.transport.sendMessage(jsonrpcNotification);
@@ -118,4 +127,5 @@ public class McpAsyncSession {
 		// TODO handle the timeout in transport
 		return Mono.fromRunnable(this.transport::close);
 	}
+
 }

src/main/java/spring/ai/mcp/client/McpSyncClient.java

@@ -4,6 +4,8 @@ import java.time.Duration;
 
 import spring.ai.mcp.spec.McpSchema;
 
+import org.springframework.util.Assert;
+
 public class McpSyncClient implements AutoCloseable {
 
 	// TODO: Consider providing a client config to set this properly
@@ -14,6 +16,7 @@ public class McpSyncClient implements AutoCloseable {
 	McpAsyncClient delegate;
 
 	public McpSyncClient(McpAsyncClient delegate) {
+		Assert.notNull(delegate, "McpAsyncClient must not be null");
 		this.delegate = delegate;
 	}
 

src/main/java/spring/ai/mcp/spec/McpSchema.java

@@ -18,6 +18,7 @@ package spring.ai.mcp.spec;
 import java.util.List;
 import java.util.Map;
 
+import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
 import com.fasterxml.jackson.annotation.JsonInclude;
 import com.fasterxml.jackson.annotation.JsonProperty;
 import com.fasterxml.jackson.annotation.JsonSubTypes;
@@ -213,6 +214,7 @@ public class McpSchema {
 	 * @param mimeType The MIME type of this resource, if known.
 	 */
 	@JsonInclude(JsonInclude.Include.NON_ABSENT)
+	@JsonIgnoreProperties(ignoreUnknown = true)
 	public record Resource( // @formatter:off
 		@JsonProperty("uri") String uri,
 		@JsonProperty("name") String name,

src/test/java/spring/ai/mcp/McpSyncClientTests.java

@@ -127,7 +127,7 @@ class McpSyncClientTests {
             .isNotNull()
             .satisfies(result -> {
                 assertThat(result.content()).isNotNull();
-                assertThat(result.isError()).isFalse();
+                assertThat(result.isError()).isNull();
             });
     }