feat: add getMetadata method for RequestContext

Author: mhyeon-lee

server-common/src/main/java/io/a2a/server/agentexecution/RequestContext.java

@@ -3,6 +3,7 @@
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
+import java.util.Map;
 import java.util.UUID;
 import java.util.stream.Collectors;
 
@@ -198,6 +199,15 @@ public List<Task> getRelatedTasks() {
         return params != null ? params.configuration() : null;
     }
 
+    /**
+     * Returns the request metadata.
+     *
+     * @return the metadata, or null if not available
+     */
+    public @Nullable Map<String, Object> getMetadata() {
+        return (params != null && params.metadata() != null) ? Collections.unmodifiableMap(params.metadata()) : null;
+    }
+
     /**
      * Returns the server call context.
      * <p>

server-common/src/test/java/io/a2a/server/agentexecution/RequestContextTest.java

@@ -10,6 +10,7 @@
 import static org.mockito.Mockito.mockStatic;
 
 import java.util.ArrayList;
+import java.util.HashMap;
 import java.util.List;
 import java.util.UUID;
 
@@ -38,6 +39,7 @@ public void testInitWithoutParams() {
         RequestContext context = new RequestContext.Builder().build();
 
         assertNull(context.getMessage());
+        assertNull(context.getMetadata());
         assertNotNull(context.getTaskId()); // Generated UUID
         assertNotNull(context.getContextId()); // Generated UUID
         assertNull(context.getTask());
@@ -70,6 +72,24 @@ public void testInitWithParamsNoIds() {
         }
     }
 
+    @Test
+    public void testInitWithParamsMetadata() {
+        var message = Message.builder().role(Message.Role.ROLE_USER).parts(List.of(new TextPart(""))).build();
+        var metadata = new HashMap<String, Object>();
+        metadata.put("key", "value");
+
+        var params = MessageSendParams.builder()
+                .message(message)
+                .metadata(metadata)
+                .build();
+
+        RequestContext context = new RequestContext.Builder()
+                .setParams(params)
+                .build();
+
+        assertEquals(metadata, context.getMetadata());
+    }
+
     @Test
     public void testInitWithTaskId() {
         String taskId = "task-123";