Review fixes

Author: JonasKunz

instrumentation/internal/internal-class-loader/javaagent/src/main/java/io/opentelemetry/javaagent/instrumentation/internal/classloader/BootDelegationInstrumentation.java

@@ -47,6 +47,10 @@ public class BootDelegationInstrumentation implements TypeInstrumentation {
   public ElementMatcher<TypeDescription> typeMatcher() {
     // just an optimization to exclude common class loaders that are known to delegate to the
     // bootstrap loader (or happen to _be_ the bootstrap loader)
+    // The AgentClassLoader and InstrumentationModuleClassloaders are required to be excluded
+    // for the instrumentation to work properly. loadClass on those is invoked during Advice
+    // bootstrapping
+    // which therefore would cause an infinite recursion
     return not(namedOneOf(
             "java.lang.ClassLoader",
             "com.ibm.oti.vm.BootstrapClassLoader",

instrumentation/internal/internal-class-loader/javaagent/src/main/java/io/opentelemetry/javaagent/instrumentation/internal/classloader/DefineClassInstrumentation.java

@@ -52,11 +52,11 @@ public static DefineClassContext onEnter(
           classLoader, className, classBytes, offset, length);
     }
 
-    // TODO: the ToReturened does nothing except for signaling the AdviceTransformer that it must
+    // TODO: the ToReturned does nothing except for signaling the AdviceTransformer that it must
     // not touch this advice
     // this is done to ensure that ClassLoaderInstrumentationModule.loadAdviceClassesEagerly works
     // correctly
-    // we can therfore remove it, as soon as the AdviceTransformer is not applied anymore
+    // we can therefore remove it, as soon as the AdviceTransformer is not applied anymore
     @Advice.OnMethodExit(onThrowable = Throwable.class, suppress = Throwable.class)
     @Advice.AssignReturned.ToReturned
     public static Class<?> onExit(
@@ -76,11 +76,11 @@ public static DefineClassContext onEnter(
       return DefineClassHelper.beforeDefineClass(classLoader, className, classBytes);
     }
 
-    // TODO: the ToReturened does nothing except for signaling the AdviceTransformer that it must
+    // TODO: the ToReturned does nothing except for signaling the AdviceTransformer that it must
     // not touch this advice
     // this is done to ensure that ClassLoaderInstrumentationModule.loadAdviceClassesEagerly works
     // correctly
-    // we can therfore remove it, as soon as the AdviceTransformer is not applied anymore
+    // we can therefore remove it, as soon as the AdviceTransformer is not applied anymore
     @Advice.OnMethodExit(onThrowable = Throwable.class, suppress = Throwable.class)
     @Advice.AssignReturned.ToReturned
     public static Class<?> onExit(

javaagent-bootstrap/src/main/java/io/opentelemetry/javaagent/bootstrap/AgentClassLoader.java

@@ -146,6 +146,7 @@ private static int getJavaVersion() {
   public Class<?> loadClass(String name) throws ClassNotFoundException {
     // We explicitly override loadClass from ClassLoader to ensure
     // that loadClass is properly excluded from our internal ClassLoader Instrumentations
+    // (e.g. LoadInjectedClassInstrumentation, BooDelegationInstrumentation)
     // Otherwise this will cause recursion in invokedynamic linkage
     return loadClass(name, false);
   }

javaagent-tooling/src/main/java/io/opentelemetry/javaagent/tooling/instrumentation/indy/InstrumentationModuleClassLoader.java

@@ -221,6 +221,7 @@ public void applyTransformer(AgentBuilder.Transformer transformer) {}
   public Class<?> loadClass(String name) throws ClassNotFoundException {
     // We explicitly override loadClass from ClassLoader to ensure
     // that loadClass is properly excluded from our internal ClassLoader Instrumentations
+    // (e.g. LoadInjectedClassInstrumentation, BooDelegationInstrumentation)
     // Otherwise this will cause recursion in invokedynamic linkage
     return loadClass(name, false);
   }