Fix #5205: Handle invalid SubscriptionMode values safely

eventmesh-common/src/main/java/org/apache/eventmesh/common/protocol/SubscriptionModeConverter.java

@@ -25,7 +25,14 @@ public class SubscriptionModeConverter implements Converter<String, Subscription
 
     @Override
     public SubscriptionMode convert(String value) {
-        return SubscriptionMode.valueOf(value);
+       if(value==null || value.trim().isEmpty()){
+        return SubscriptionMode.UNRECOGNIZED;
+       }
+       try{
+        return SubscriptionMode.valueOf(value.trim().toUpperCase());
+       }catch (IllegalArgumentException e ){
+         return SubscriptionMode.UNRECOGNIZED;
+       }
     }
 
     @Override

eventmesh-common/src/test/java/org/apache/eventmesh/common/protocol/SubscriptionModeConverterTest.java

@@ -0,0 +1,46 @@
+package org.apache.eventmesh.common.protocol;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class SubscriptionModeConverterTest {
+
+    private final SubscriptionModeConverter converter = new SubscriptionModeConverter();
+
+    @Test
+    public void testValidBroadcasting() {
+        SubscriptionMode result = converter.convert("BROADCASTING");
+        assertEquals(SubscriptionMode.BROADCASTING, result);
+    }
+
+    @Test
+    public void testValidClusteringLowerCase() {
+        SubscriptionMode result = converter.convert("clustering");
+        assertEquals(SubscriptionMode.CLUSTERING, result);
+    }
+
+    @Test
+    public void testValidWithSpaces() {
+        SubscriptionMode result = converter.convert("  broadcasting  ");
+        assertEquals(SubscriptionMode.BROADCASTING, result);
+    }
+
+    @Test
+    public void testNullValue() {
+        SubscriptionMode result = converter.convert(null);
+        assertEquals(SubscriptionMode.UNRECOGNIZED, result);
+    }
+
+    @Test
+    public void testEmptyValue() {
+        SubscriptionMode result = converter.convert("");
+        assertEquals(SubscriptionMode.UNRECOGNIZED, result);
+    }
+
+    @Test
+    public void testInvalidValue() {
+        SubscriptionMode result = converter.convert("invalid_value");
+        assertEquals(SubscriptionMode.UNRECOGNIZED, result);
+    }
+}