[fix][broker] Fix can't send ErrorCommand when message is null value (#19899)

Author: coderzc

pulsar-broker/src/test/java/org/apache/pulsar/client/api/ClientErrorsTest.java

@@ -22,16 +22,15 @@
 import static org.testng.Assert.assertFalse;
 import static org.testng.Assert.assertTrue;
 import static org.testng.Assert.fail;
-
 import io.netty.channel.ChannelHandlerContext;
-
+import java.util.Map;
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicInteger;
 import java.util.concurrent.atomic.AtomicReference;
-
 import lombok.Cleanup;
+import org.apache.bookkeeper.common.util.JsonUtil;
 import org.apache.pulsar.client.impl.ConsumerBase;
 import org.apache.pulsar.client.impl.PartitionedProducerImpl;
 import org.apache.pulsar.client.impl.ProducerBase;
@@ -831,4 +830,28 @@ public void testConsumerReconnect() throws Exception {
         mockBrokerService.resetHandleConnect();
         mockBrokerService.resetHandleSubscribe();
     }
+
+    @Test
+    public void testCommandErrorMessageIsNull() throws Exception {
+        @Cleanup
+        PulsarClient client = PulsarClient.builder().serviceUrl(mockBrokerService.getBrokerAddress()).build();
+
+        mockBrokerService.setHandleProducer((ctx, producer) -> {
+            try {
+                ctx.writeAndFlush(Commands.newError(producer.getRequestId(), ServerError.AuthorizationError, null));
+            } catch (Exception e) {
+                fail("Send error command failed", e);
+            }
+        });
+
+        try {
+            client.newProducer().topic("persistent://prop/use/ns/t1").create();
+            fail();
+        } catch (Exception e) {
+            assertTrue(e instanceof PulsarClientException.AuthorizationException);
+            Map<String, String> map = JsonUtil.fromJson(e.getMessage(), Map.class);
+            assertEquals(map.get("errorMsg"), "");
+        }
+        mockBrokerService.resetHandleProducer();
+    }
 }

pulsar-common/src/main/java/org/apache/pulsar/common/protocol/Commands.java

@@ -367,7 +367,7 @@ public static BaseCommand newErrorCommand(long requestId, ServerError serverErro
         cmd.setError()
                 .setRequestId(requestId)
                 .setError(serverError)
-                .setMessage(message);
+                .setMessage(message != null ? message : "");
         return cmd;
     }
 
@@ -400,7 +400,7 @@ public static BaseCommand newSendErrorCommand(long producerId, long sequenceId,
                 .setProducerId(producerId)
                 .setSequenceId(sequenceId)
                 .setError(error)
-                .setMessage(errorMsg);
+                .setMessage(errorMsg != null ? errorMsg : "");
         return cmd;
     }