opti test and add javadoc

Author: hqbfzwang

pulsar-client/src/main/java/org/apache/pulsar/client/impl/metrics/ConsumerMetrics.java

@@ -20,6 +20,11 @@
 
 import io.opentelemetry.api.common.Attributes;
 
+/**
+ * Encapsulates OpenTelemetry metrics for a Pulsar consumer, tracking message receives,
+ * prefetch queue size, acknowledgements, negative acknowledgements, dead-letter queue
+ * messages, and consumer session open/close events.
+ */
 public class ConsumerMetrics {
 
     private final Counter messagesReceivedCounter;

pulsar-client/src/main/java/org/apache/pulsar/client/impl/metrics/ProducerMetrics.java

@@ -20,6 +20,11 @@
 
 import io.opentelemetry.api.common.Attributes;
 
+/**
+ * Encapsulates OpenTelemetry metrics for a Pulsar producer, tracking message send latency,
+ * RPC latency, published bytes, pending queue message count and size, and producer session
+ * open/close events.
+ */
 public class ProducerMetrics {
 
     private final LatencyHistogram sendLatencyHistogram;

pulsar-client/src/test/java/org/apache/pulsar/client/impl/OpSendMsgQueueTest.java

@@ -24,6 +24,7 @@
 import com.google.common.collect.Lists;
 import java.util.Arrays;
 import java.util.Iterator;
+import org.apache.pulsar.client.impl.metrics.InstrumentProvider;
 import org.apache.pulsar.client.impl.metrics.ProducerMetrics;
 import org.testng.annotations.BeforeClass;
 import org.testng.annotations.Test;
@@ -32,6 +33,9 @@
  * Contains unit tests for ProducerImpl.OpSendMsgQueue inner class.
  */
 public class OpSendMsgQueueTest {
+    private static final ProducerMetrics NOOP_PRODUCER_METRICS =
+            new ProducerMetrics(InstrumentProvider.NOOP, "test-topic");
+
     MessageImpl<?> message;
 
     @BeforeClass
@@ -41,7 +45,7 @@ public void createMockMessage() {
     }
 
     private ProducerImpl.OpSendMsg createDummyOpSendMsg() {
-        return ProducerImpl.OpSendMsg.create((ProducerMetrics) null, message, null, 0L, null);
+        return ProducerImpl.OpSendMsg.create(NOOP_PRODUCER_METRICS, message, null, 0L, null);
     }
 
     @Test

pulsar-client/src/test/java/org/apache/pulsar/client/impl/ProducerImplTest.java

@@ -30,13 +30,17 @@
 import org.apache.commons.lang3.reflect.FieldUtils;
 import org.apache.pulsar.client.api.PulsarClientException;
 import org.apache.pulsar.client.api.Schema;
+import org.apache.pulsar.client.impl.metrics.InstrumentProvider;
 import org.apache.pulsar.client.impl.metrics.ProducerMetrics;
 import org.apache.pulsar.common.api.proto.MessageMetadata;
 import org.apache.pulsar.common.protocol.ByteBufPair;
 import org.mockito.Mockito;
 import org.testng.annotations.Test;
 
 public class ProducerImplTest {
+    private static final ProducerMetrics NOOP_PRODUCER_METRICS =
+            new ProducerMetrics(InstrumentProvider.NOOP, "test-topic");
+
     @Test
     public void testChunkedMessageCtxDeallocate() {
         int totalChunks = 3;
@@ -47,7 +51,7 @@ public void testChunkedMessageCtxDeallocate() {
         for (int i = 0; i < totalChunks; i++) {
             ProducerImpl.OpSendMsg opSendMsg =
                     ProducerImpl.OpSendMsg.create(
-                            (ProducerMetrics) null,
+                            NOOP_PRODUCER_METRICS,
                             MessageImpl.create(new MessageMetadata(), ByteBuffer.allocate(0), Schema.STRING, null),
                             null, 0, null);
             opSendMsg.chunkedMessageCtx = ctx;
@@ -103,7 +107,7 @@ public void testFailPendingMessagesSyncRetry()
         MessageImpl<?> msg = Mockito.mock(MessageImpl.class);
         Mockito.when(msg.getUncompressedSize()).thenReturn(10);
         ProducerImpl.OpSendMsg op = ProducerImpl.OpSendMsg.create(
-                (ProducerMetrics) null,
+                NOOP_PRODUCER_METRICS,
                 msg,
                 Mockito.mock(ByteBufPair.class),
                 1L,
@@ -121,7 +125,7 @@ public void testFailPendingMessagesSyncRetry()
         Mockito.doAnswer(invocation -> {
             // Reentrant retry during callback
             ProducerImpl.OpSendMsg retryOp = ProducerImpl.OpSendMsg.create(
-                    (ProducerMetrics) null,
+                    NOOP_PRODUCER_METRICS,
                     retryMsg,
                     Mockito.mock(ByteBufPair.class),
                     2L,