Review fixes for apache-dubbo-2.7:library-autoconfigure (#16482)

Co-authored-by: otelbot <197425009+otelbot@users.noreply.github.com>

Author: otelbot[bot]

instrumentation/apache-dubbo-2.7/library-autoconfigure/src/main/java/io/opentelemetry/instrumentation/apachedubbo/v2_7/DubboHeadersGetter.java

@@ -10,10 +10,10 @@
 import java.lang.invoke.MethodHandles;
 import java.lang.invoke.MethodType;
 import java.util.Map;
+import javax.annotation.Nullable;
 import org.apache.dubbo.rpc.RpcInvocation;
 
-enum DubboHeadersGetter implements TextMapGetter<DubboRequest> {
-  INSTANCE;
+final class DubboHeadersGetter implements TextMapGetter<DubboRequest> {
 
   private static final MethodHandle GET_OBJECT_ATTACHMENTS;
 
@@ -48,7 +48,10 @@ public Iterable<String> keys(DubboRequest request) {
 
   @Override
   @SuppressWarnings("deprecation") // deprecation for dubbo 3.2.15
-  public String get(DubboRequest request, String key) {
+  public String get(@Nullable DubboRequest request, String key) {
+    if (request == null) {
+      return null;
+    }
     return request.invocation().getAttachment(key);
   }
 }

instrumentation/apache-dubbo-2.7/library-autoconfigure/src/main/java/io/opentelemetry/instrumentation/apachedubbo/v2_7/DubboHeadersSetter.java

@@ -6,12 +6,15 @@
 package io.opentelemetry.instrumentation.apachedubbo.v2_7;
 
 import io.opentelemetry.context.propagation.TextMapSetter;
+import javax.annotation.Nullable;
 
-enum DubboHeadersSetter implements TextMapSetter<DubboRequest> {
-  INSTANCE;
+final class DubboHeadersSetter implements TextMapSetter<DubboRequest> {
 
   @Override
-  public void set(DubboRequest request, String key, String value) {
+  public void set(@Nullable DubboRequest request, String key, String value) {
+    if (request == null) {
+      return;
+    }
     request.context().setAttachment(key, value);
     request.invocation().setAttachment(key, value);
   }

instrumentation/apache-dubbo-2.7/library-autoconfigure/src/main/java/io/opentelemetry/instrumentation/apachedubbo/v2_7/DubboRpcAttributesGetter.java

@@ -9,8 +9,7 @@
 import javax.annotation.Nullable;
 import org.apache.dubbo.rpc.Result;
 
-enum DubboRpcAttributesGetter implements RpcAttributesGetter<DubboRequest, Result> {
-  INSTANCE;
+final class DubboRpcAttributesGetter implements RpcAttributesGetter<DubboRequest, Result> {
 
   @Override
   public String getRpcSystemName(DubboRequest request) {

instrumentation/apache-dubbo-2.7/library-autoconfigure/src/main/java/io/opentelemetry/instrumentation/apachedubbo/v2_7/DubboTelemetryBuilder.java

@@ -80,7 +80,7 @@ public DubboTelemetryBuilder setServerSpanNameExtractorCustomizer(
    */
   @SuppressWarnings("deprecation") // RpcMetricsContextCustomizers is deprecated for removal in 3.0
   public DubboTelemetry build() {
-    DubboRpcAttributesGetter rpcAttributesGetter = DubboRpcAttributesGetter.INSTANCE;
+    DubboRpcAttributesGetter rpcAttributesGetter = new DubboRpcAttributesGetter();
     SpanNameExtractor<DubboRequest> spanNameExtractor =
         RpcSpanNameExtractor.create(rpcAttributesGetter);
     SpanNameExtractor<DubboRequest> clientSpanNameExtractor =
@@ -114,7 +114,7 @@ public DubboTelemetry build() {
                 RpcMetricsContextCustomizers.dualEmitContextCustomizer(rpcAttributesGetter));
 
     return new DubboTelemetry(
-        serverInstrumenterBuilder.buildServerInstrumenter(DubboHeadersGetter.INSTANCE),
-        clientInstrumenterBuilder.buildClientInstrumenter(DubboHeadersSetter.INSTANCE));
+        serverInstrumenterBuilder.buildServerInstrumenter(new DubboHeadersGetter()),
+        clientInstrumenterBuilder.buildClientInstrumenter(new DubboHeadersSetter()));
   }
 }

instrumentation/apache-dubbo-2.7/library-autoconfigure/src/test/java/io/opentelemetry/instrumentation/apachedubbo/v2_7/DubboHeadersGetterTest.java

@@ -40,7 +40,7 @@ void testKeys() throws Exception {
     }
     DubboRequest request = DubboRequest.create(rpcInvocation, context);
 
-    Iterator<String> iterator = DubboHeadersGetter.INSTANCE.keys(request).iterator();
+    Iterator<String> iterator = new DubboHeadersGetter().keys(request).iterator();
     assertThat(iterator.hasNext()).isTrue();
     assertThat(iterator.next()).isEqualTo("key");
     assertThat(iterator.hasNext()).isFalse();