Apply method instrumentation only to methods (open-telemetry#13949)

Author: laurit

instrumentation/methods/javaagent/src/main/java/io/opentelemetry/javaagent/instrumentation/methods/MethodInstrumentation.java

@@ -10,6 +10,7 @@
 import static io.opentelemetry.javaagent.extension.matcher.AgentElementMatchers.hasSuperType;
 import static io.opentelemetry.javaagent.instrumentation.methods.MethodSingletons.getBootstrapLoader;
 import static io.opentelemetry.javaagent.instrumentation.methods.MethodSingletons.instrumenter;
+import static net.bytebuddy.matcher.ElementMatchers.isMethod;
 import static net.bytebuddy.matcher.ElementMatchers.named;
 import static net.bytebuddy.matcher.ElementMatchers.namedOneOf;
 
@@ -55,7 +56,7 @@ public ElementMatcher<TypeDescription> typeMatcher() {
   @Override
   public void transform(TypeTransformer transformer) {
     transformer.applyAdviceToMethod(
-        namedOneOf(methodNames.toArray(new String[0])),
+        namedOneOf(methodNames.toArray(new String[0])).and(isMethod()),
         mapping ->
             mapping.bind(
                 MethodReturnType.class,