Introduce JSpecify

Replace Reactor @nullable with JSpecify.

Signed-off-by: Daniel Garnier-Moiroux <git@garnier.wf>

Author: Kehrlann

mcp-core/pom.xml

@@ -82,6 +82,12 @@
 			<version>${jackson-annotations.version}</version>
 		</dependency>
 
+		<dependency>
+			<groupId>org.jspecify</groupId>
+			<artifactId>jspecify</artifactId>
+			<version>${jspecify.version}</version>
+		</dependency>
+
 		<dependency>
 			<groupId>io.projectreactor</groupId>
 			<artifactId>reactor-core</artifactId>

mcp-core/src/main/java/io/modelcontextprotocol/client/transport/customizer/McpAsyncHttpClientRequestCustomizer.java

@@ -12,7 +12,7 @@
 import org.reactivestreams.Publisher;
 import reactor.core.publisher.Mono;
 import reactor.core.scheduler.Schedulers;
-import reactor.util.annotation.Nullable;
+import org.jspecify.annotations.Nullable;
 
 /**
  * Customize {@link HttpRequest.Builder} before executing the request, in either SSE or

mcp-core/src/main/java/io/modelcontextprotocol/client/transport/customizer/McpSyncHttpClientRequestCustomizer.java

@@ -7,7 +7,7 @@
 import java.net.URI;
 import java.net.http.HttpRequest;
 
-import reactor.util.annotation.Nullable;
+import org.jspecify.annotations.Nullable;
 
 import io.modelcontextprotocol.client.McpClient.SyncSpec;
 import io.modelcontextprotocol.common.McpTransportContext;

mcp-core/src/main/java/io/modelcontextprotocol/modern/server/McpParamHeaders.java

@@ -13,7 +13,7 @@
 
 import io.modelcontextprotocol.modern.McpHttp;
 import io.modelcontextprotocol.util.Assert;
-import reactor.util.annotation.Nullable;
+import org.jspecify.annotations.Nullable;
 
 /**
  * The {@code Mcp-Param-{Name}} headers of a {@code tools/call} request, which a client
@@ -90,8 +90,7 @@ public boolean isMalformed(String name) {
 	 * @param name the {@code {Name}} part of {@code Mcp-Param-{Name}}, in any case
 	 * @return the decoded value, or {@code null} if the header is absent or malformed
 	 */
-	@Nullable
-	public String value(String name) {
+	@Nullable public String value(String name) {
 		return this.values.get(normalize(name));
 	}
 

mcp-core/src/main/java/io/modelcontextprotocol/modern/server/transport/McpHeaderDecoder.java

@@ -20,7 +20,7 @@
 import io.modelcontextprotocol.modern.McpHttp.Headers;
 import io.modelcontextprotocol.modern.server.McpParamHeaders;
 import io.modelcontextprotocol.server.transport.HeaderAccessor;
-import reactor.util.annotation.Nullable;
+import org.jspecify.annotations.Nullable;
 
 /**
  * Strict decoder for MCP header values such as {@code Mcp-Name} and
@@ -50,8 +50,7 @@ private McpHeaderDecoder() {
 	 * @param raw the header value as received
 	 * @return the decoded value, or {@code null} if the value is malformed
 	 */
-	@Nullable
-	public static String decodeValue(String raw) {
+	@Nullable public static String decodeValue(String raw) {
 		if (raw.length() >= Headers.BASE64_VALUE_PREFIX.length() + Headers.BASE64_VALUE_SUFFIX.length()
 				&& raw.startsWith(Headers.BASE64_VALUE_PREFIX) && raw.endsWith(Headers.BASE64_VALUE_SUFFIX)) {
 			String encoded = raw.substring(Headers.BASE64_VALUE_PREFIX.length(),

mcp-core/src/main/java/io/modelcontextprotocol/spec/ClosedMcpTransportSession.java

@@ -8,7 +8,7 @@
 import org.reactivestreams.Publisher;
 import reactor.core.Disposable;
 import reactor.core.publisher.Mono;
-import reactor.util.annotation.Nullable;
+import org.jspecify.annotations.Nullable;
 
 /**
  * Represents a closed MCP session, which may not be reused.

mcp-core/src/main/java/io/modelcontextprotocol/spec/McpTransportSessionClosedException.java

@@ -4,7 +4,7 @@
 
 package io.modelcontextprotocol.spec;
 
-import reactor.util.annotation.Nullable;
+import org.jspecify.annotations.Nullable;
 
 /**
  * Exception thrown when trying to use an {@link McpTransportSession} that has been

mcp-core/src/main/java/io/modelcontextprotocol/util/Assert.java

@@ -6,7 +6,7 @@
 
 import java.util.Collection;
 
-import reactor.util.annotation.Nullable;
+import org.jspecify.annotations.Nullable;
 
 /**
  * Assertion utility class that assists in validating arguments.

mcp-core/src/main/java/io/modelcontextprotocol/util/Utils.java

@@ -8,7 +8,7 @@
 import java.util.Collection;
 import java.util.Map;
 
-import reactor.util.annotation.Nullable;
+import org.jspecify.annotations.Nullable;
 
 /**
  * Miscellaneous utility methods.

mcp-test/pom.xml

@@ -37,6 +37,12 @@
 			<version>${slf4j-api.version}</version>
 		</dependency>
 
+		<dependency>
+			<groupId>org.jspecify</groupId>
+			<artifactId>jspecify</artifactId>
+			<version>${jspecify.version}</version>
+		</dependency>
+
 		<dependency>
 			<groupId>io.projectreactor</groupId>
 			<artifactId>reactor-core</artifactId>