Demonstrating how JNI makes true private state in Java impossible

build.sh

# These commands are OS-dependent, this only works on Mac
javac Main.java -h .
gcc Main.c -o libSecret.dylib -shared -I"$JAVA_HOME/include" -I"$JAVA_HOME/include/darwin"
java Main

Main.c

#include <jni.h>
#include "Main.h"

JNIEXPORT jobject JNICALL Java_Main_getSecret(JNIEnv *env, jobject obj, jobject secretObj)
{
    jclass cls = (*env)->GetObjectClass(env, secretObj);
    jfieldID field_id = (*env)->GetFieldID(env, cls, "secret", "Ljava/lang/Object;");
    jobject secret = (*env)->GetObjectField(env, secretObj, field_id);
    return secret;
}

Main.java

public class Main {
    static {
        System.loadLibrary("Secret");
    }

    private native Object getSecret(Secret secret);

    public static void main(String[] args) {
        Secret secret = new Secret(Character.toString(65).repeat(10));
         // "indirect access" as defined in my blog, 
        System.out.println(secret.get()) // outputs: AAAAAAAAA
        // "direct access" as defined in my blog
        System.out.println(new Main().getSecret(secret)); // also outputs: AAAAAAAAA
    }
}

Secret.java

public class Secret {
    private Object secret;

    public Secret(Object secret) {
        this.secret = secret;
    }

    public Object get() {
        return secret;
    }
}