use optional instead of providing default for list

Author: zeitlinger

instrumentation-api/src/main/java/io/opentelemetry/instrumentation/api/internal/ConfigPropertiesUtil.java

@@ -6,6 +6,7 @@
 package io.opentelemetry.instrumentation.api.internal;
 
 import static io.opentelemetry.api.incubator.config.DeclarativeConfigProperties.empty;
+import static java.util.Collections.emptyList;
 
 import io.opentelemetry.api.OpenTelemetry;
 import io.opentelemetry.api.incubator.ExtendedOpenTelemetry;
@@ -125,15 +126,14 @@ public static String getStringOrFallback(
    * Returns the list of strings value of the given property name from Declarative Config if
    * available, otherwise falls back to system properties and environment variables.
    */
-  public static List<String> getList(
-      OpenTelemetry openTelemetry, List<String> defaultValue, String... propertyName) {
+  public static List<String> getList(OpenTelemetry openTelemetry, String... propertyName) {
     DeclarativeConfigProperties node = getDeclarativeConfigNode(openTelemetry, propertyName);
     if (node != null) {
-      return node.getScalarList(leaf(propertyName), String.class, defaultValue);
+      return node.getScalarList(leaf(propertyName), String.class, emptyList());
     }
     String value = getString(toSystemProperty(propertyName));
     if (value == null) {
-      return defaultValue;
+      return emptyList();
     }
     return filterBlanksAndNulls(value.split(","));
   }

instrumentation-api/src/test/java/io/opentelemetry/instrumentation/api/internal/ConfigPropertiesUtilTest.java

@@ -199,9 +199,7 @@ void getList_none() {
   }
 
   private static void assertList(List<String> expected) {
-    assertThat(
-            ConfigPropertiesUtil.getList(
-                OpenTelemetry.noop(), emptyList(), "test", "property", "list"))
+    assertThat(ConfigPropertiesUtil.getList(OpenTelemetry.noop(), "test", "property", "list"))
         .isEqualTo(expected);
   }
 
@@ -219,7 +217,7 @@ public static Stream<Arguments> listValuesProvider() {
   void getList_declarativeConfig(Object property, List<String> expected) {
     assertThat(
             ConfigPropertiesUtil.getList(
-                DeclarativeConfiguration.create(model(property)), emptyList(), "foo", "bar"))
+                DeclarativeConfiguration.create(model(property)), "foo", "bar"))
         .isEqualTo(expected);
   }
 }

instrumentation/aws-sdk/aws-sdk-1.11/library-autoconfigure/src/main/java/io/opentelemetry/instrumentation/awssdk/v1_11/autoconfigure/TracingRequestHandler.java

@@ -5,8 +5,6 @@
 
 package io.opentelemetry.instrumentation.awssdk.v1_11.autoconfigure;
 
-import static java.util.Collections.emptyList;
-
 import com.amazonaws.AmazonWebServiceRequest;
 import com.amazonaws.Request;
 import com.amazonaws.Response;
@@ -35,7 +33,7 @@ private static RequestHandler2 buildDelegate(OpenTelemetry openTelemetry) {
                 .orElse(false))
         .setCapturedHeaders(
             ConfigPropertiesUtil.getList(
-                openTelemetry, emptyList(), "messaging", "experimental", "capture_headers"))
+                openTelemetry, "messaging", "experimental", "capture_headers"))
         .build()
         .newRequestHandler();
   }

instrumentation/aws-sdk/aws-sdk-2.2/library-autoconfigure/src/main/java/io/opentelemetry/instrumentation/awssdk/v2_2/autoconfigure/AwsSdkSingletons.java

@@ -5,8 +5,6 @@
 
 package io.opentelemetry.instrumentation.awssdk.v2_2.autoconfigure;
 
-import static java.util.Collections.emptyList;
-
 import io.opentelemetry.api.GlobalOpenTelemetry;
 import io.opentelemetry.instrumentation.api.internal.ConfigPropertiesUtil;
 import io.opentelemetry.instrumentation.awssdk.v2_2.AwsSdkTelemetry;
@@ -26,7 +24,7 @@ private static class AwsSdkTelemetryFactory extends AbstractAwsSdkTelemetryFacto
     @Override
     protected List<String> getCapturedHeaders() {
       return ConfigPropertiesUtil.getList(
-          GlobalOpenTelemetry.get(), emptyList(), "messaging", "experimental", "capture_headers");
+          GlobalOpenTelemetry.get(), "messaging", "experimental", "capture_headers");
     }
 
     @Override

instrumentation/kafka/kafka-clients/kafka-clients-2.6/library/src/main/java/io/opentelemetry/instrumentation/kafkaclients/v2_6/TracingConsumerInterceptor.java

@@ -5,8 +5,6 @@
 
 package io.opentelemetry.instrumentation.kafkaclients.v2_6;
 
-import static java.util.Collections.emptyList;
-
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import io.opentelemetry.api.GlobalOpenTelemetry;
 import io.opentelemetry.api.OpenTelemetry;
@@ -45,7 +43,7 @@ public class TracingConsumerInterceptor<K, V> implements ConsumerInterceptor<K,
                     .orElse(false))
             .setCapturedHeaders(
                 ConfigPropertiesUtil.getList(
-                    openTelemetry, emptyList(), "messaging", "experimental", "capture_headers"))
+                    openTelemetry, "messaging", "experimental", "capture_headers"))
             .build();
   }
 

instrumentation/kafka/kafka-clients/kafka-clients-2.6/library/src/main/java/io/opentelemetry/instrumentation/kafkaclients/v2_6/TracingProducerInterceptor.java

@@ -5,8 +5,6 @@
 
 package io.opentelemetry.instrumentation.kafkaclients.v2_6;
 
-import static java.util.Collections.emptyList;
-
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import io.opentelemetry.api.GlobalOpenTelemetry;
 import io.opentelemetry.api.OpenTelemetry;
@@ -37,7 +35,7 @@ public class TracingProducerInterceptor<K, V> implements ProducerInterceptor<K,
         KafkaTelemetry.builder(openTelemetry)
             .setCapturedHeaders(
                 ConfigPropertiesUtil.getList(
-                    openTelemetry, emptyList(), "messaging", "experimental", "capture_headers"))
+                    openTelemetry, "messaging", "experimental", "capture_headers"))
             .build();
   }