Simplify boot prefix handling

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

@@ -17,9 +17,11 @@
 import static net.bytebuddy.matcher.ElementMatchers.takesArgument;
 import static net.bytebuddy.matcher.ElementMatchers.takesArguments;
 
+import io.opentelemetry.javaagent.bootstrap.BootstrapPackagePrefixesHolder;
 import io.opentelemetry.javaagent.bootstrap.CallDepth;
 import io.opentelemetry.javaagent.extension.instrumentation.TypeInstrumentation;
 import io.opentelemetry.javaagent.extension.instrumentation.TypeTransformer;
+import java.util.List;
 import net.bytebuddy.asm.Advice;
 import net.bytebuddy.asm.Advice.AssignReturned;
 import net.bytebuddy.description.method.MethodDescription;
@@ -68,7 +70,13 @@ public void transform(TypeTransformer transformer) {
   public static class LoadClassAdvice {
 
     @Advice.OnMethodEnter(skipOn = Advice.OnNonDefaultValue.class)
-    public static Class<?> onEnter(@Advice.Argument(0) String name) {
+    public static Class<?> onEnter(
+        @Advice.This ClassLoader classLoader, @Advice.Argument(0) String name) {
+      // must be read before call depth is incremented as setting the call depth prevents the class
+      // loader of the instrumented class from loading BootstrapPackagePrefixesHolder itself
+      List<String> bootstrapPackagePrefixes =
+          BootstrapPackagePrefixesHolder.getBootstrapPackagePrefixes();
+
       // need to use call depth here to prevent re-entry from call to Class.forName() below
       // because on some JVMs (e.g. IBM's, though IBM bootstrap loader is explicitly excluded above)
       // Class.forName() ends up calling loadClass() on the bootstrap loader which would then come
@@ -80,7 +88,7 @@ public static Class<?> onEnter(@Advice.Argument(0) String name) {
       }
 
       try {
-        for (String prefix : BootstrapPackagesHelper.bootstrapPackagesPrefixes) {
+        for (String prefix : bootstrapPackagePrefixes) {
           if (name.startsWith(prefix)) {
             try {
               return Class.forName(name, false, null);

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

@@ -12,7 +12,6 @@
 import io.opentelemetry.javaagent.extension.instrumentation.TypeInstrumentation;
 import io.opentelemetry.javaagent.extension.instrumentation.internal.ExperimentalInstrumentationModule;
 import io.opentelemetry.sdk.autoconfigure.spi.ConfigProperties;
-import java.util.Arrays;
 import java.util.List;
 
 @AutoService(InstrumentationModule.class)
@@ -28,13 +27,6 @@ public boolean defaultEnabled(ConfigProperties config) {
     return true;
   }
 
-  @Override
-  public List<String> getAdditionalHelperClassNames() {
-    return Arrays.asList(
-        "io.opentelemetry.javaagent.instrumentation.internal.classloader.BootstrapPackagesHelper",
-        "io.opentelemetry.javaagent.tooling.Constants");
-  }
-
   @Override
   public List<String> injectedClassNames() {
     return getAdditionalHelperClassNames();

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

@@ -20,7 +20,7 @@ public final class BootstrapPackagePrefixesHolder {
 
   private static volatile List<String> bootstrapPackagePrefixes;
 
-  public static List<String> getBoostrapPackagePrefixes() {
+  public static List<String> getBootstrapPackagePrefixes() {
     return bootstrapPackagePrefixes;
   }
 

testing-common/integration-tests/src/test/java/instrumentation/AgentInstrumentationTest.java

@@ -39,7 +39,7 @@ class AgentInstrumentationTest {
 
   private static final ClassLoader BOOTSTRAP_CLASSLOADER = null;
   private static final List<String> BOOTSTRAP_PACKAGE_PREFIXES =
-      BootstrapPackagePrefixesHolder.getBoostrapPackagePrefixes();
+      BootstrapPackagePrefixesHolder.getBootstrapPackagePrefixes();
 
   @RegisterExtension
   static final InstrumentationExtension testing = AgentInstrumentationExtension.create();