Optimize codes

Author: steverao

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

@@ -14,7 +14,7 @@
  */
 public final class ServiceLoaderUtil {
 
-  private static Function<Class<?>, Iterable<?>> loadFunction = ServiceLoader::load;
+  private static volatile Function<Class<?>, Iterable<?>> loadFunction = ServiceLoader::load;
 
   private ServiceLoaderUtil() {}
 

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

@@ -78,7 +78,7 @@ class InstrumentationCustomizerTest {
   private List<InternalInstrumenterCustomizerProvider> originalCustomizerProviders;
 
   @BeforeEach
-  void setUp() {
+  void beforeEach() {
     originalCustomizerProviders =
         InternalInstrumenterCustomizerUtil.getInstrumenterCustomizerProviders();
   }