Add the sse-websocket module

sse-websocket/pom.xml

@@ -0,0 +1,59 @@
+<project xmlns="http://maven.apache.org/POM/4.0.0">
+  <modelVersion>4.0.0</modelVersion>
+
+  <parent>
+    <groupId>org.springframework.boot</groupId>
+    <artifactId>spring-boot-starter-parent</artifactId>
+    <version>4.1.1</version>
+    <relativePath/>
+  </parent>
+
+  <groupId>com.ankurm</groupId>
+  <artifactId>sse-websocket</artifactId>
+  <version>1.0</version>
+  <packaging>jar</packaging>
+
+  <properties>
+    <java.version>25</java.version>
+    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+  </properties>
+
+  <dependencies>
+    <!-- SseEmitter lives in spring-webmvc, so the web starter is all SSE needs. There is no
+         "SSE starter" and no SSE auto-configuration: it is a return type, not a subsystem. -->
+    <dependency>
+      <groupId>org.springframework.boot</groupId>
+      <artifactId>spring-boot-starter-webmvc</artifactId>
+    </dependency>
+
+    <!-- spring-boot-starter-websocket, NOT a bare org.springframework:spring-websocket.
+         In Boot 4 the auto-configuration lives in the spring-boot-websocket module. Depending
+         on spring-websocket + spring-messaging directly compiles and starts, and then the
+         handshake 404s because no WebSocketUpgrade/ServerContainer is configured. Same rule as
+         spring-kafka in ../kafka-basics. See docs/01-two-protocols.md. -->
+    <dependency>
+      <groupId>org.springframework.boot</groupId>
+      <artifactId>spring-boot-starter-websocket</artifactId>
+    </dependency>
+
+    <dependency>
+      <groupId>org.springframework.boot</groupId>
+      <artifactId>spring-boot-starter-jackson</artifactId>
+    </dependency>
+
+    <dependency>
+      <groupId>org.springframework.boot</groupId>
+      <artifactId>spring-boot-starter-test</artifactId>
+      <scope>test</scope>
+    </dependency>
+  </dependencies>
+
+  <build>
+    <plugins>
+      <plugin>
+        <groupId>org.springframework.boot</groupId>
+        <artifactId>spring-boot-maven-plugin</artifactId>
+      </plugin>
+    </plugins>
+  </build>
+</project>