ClassFileTransformer.transform() can be passed null protectionDomain

Agent.java

import java.lang.instrument.Instrumentation;

public class Agent {
    public static void premain(String agentArgs, Instrumentation instrumentation) {
        instrumentation.addTransformer(new Transformer());
    }
}

MANIFEST.MF

Premain-Class: Agent

SAMPLE OUTPUT

java/lang/invoke/MethodHandleImpl passed in with null protection domain
java/lang/invoke/MemberName$Factory passed in with null protection domain
java/lang/invoke/LambdaForm$NamedFunction passed in with null protection domain
java/lang/invoke/MethodType$ConcurrentWeakInternSet passed in with null protection domain
java/lang/invoke/MethodHandleStatics passed in with null protection domain
java/lang/invoke/MethodHandleStatics$1 passed in with null protection domain
java/lang/invoke/MethodTypeForm passed in with null protection domain
java/lang/invoke/Invokers passed in with null protection domain
java/lang/invoke/MethodType$ConcurrentWeakInternSet$WeakEntry passed in with null protection domain
java/lang/Void passed in with null protection domain
java/lang/IllegalAccessException passed in with null protection domain
sun/misc/PostVMInitHook passed in with null protection domain
java version "1.8.0_05"
Java(TM) SE Runtime Environment (build 1.8.0_05-b13)
Java HotSpot(TM) 64-Bit Server VM (build 25.5-b02, mixed mode)
java/lang/Shutdown passed in with null protection domain
java/lang/Shutdown$Lock passed in with null protection domain

test.sh

#!/bin/sh

javac Agent.java Transformer.java
jar cmf MANIFEST.MF agent.jar Agent.class Transformer.class
java -javaagent:agent.jar -version

Transformer.java

import java.lang.instrument.ClassFileTransformer;
import java.lang.instrument.IllegalClassFormatException;
import java.security.ProtectionDomain;

public class Transformer implements ClassFileTransformer {
    @Override
    public byte[] transform(ClassLoader loader, String className, Class<?> classBeingRedefined,
            ProtectionDomain protectionDomain, byte[] classfileBuffer)
            throws IllegalClassFormatException {
        if (protectionDomain == null) {
            System.out.println(className + " passed in with null protection domain");
        }
        return null;
    }
}