Overridding a package private package.

PackageConfustion.java

import net.bytebuddy.dynamic.loading.ClassLoadingStrategy;
import net.bytebuddy.implementation.FixedValue;

import java.lang.reflect.Method;

import static net.bytebuddy.matcher.ElementMatchers.named;

public class PackageConfusion {

    public static void main(String[] args) throws Exception {
        Sample sample = new ByteBuddy()
                .subclass(Sample.class)
                .method(named("value"))
                .intercept(FixedValue.value("bar"))
                .make()
                .load(Sample.class.getClassLoader(), ClassLoadingStrategy.Default.WRAPPER) // Change to 'INJECTION' for current class loader
                .getLoaded()
                .newInstance();

        System.out.println(sample.value());

        Method method = sample.getClass().getDeclaredMethod("value"); // Invoke 'value' that is owned by other class loader
        method.setAccessible(true);
        System.out.println(method.invoke(sample));
    }

    public static class Sample {

        String value() {
            return "foo";
        }
    }
}