The string returned by toString() shows the bridge methods as having the volatile modificator.

Run the following code:

import java.lang.reflect.Method;

public class BridgeMethodTest {

    public static void main(String[] args) throws ClassNotFoundException {
        Class cl = Class.forName("java.lang.String");
        for(Method m : cl.getDeclaredMethods()) {
            if (m.isBridge())
                System.out.println(m);
        }
    }
}

The result is:
public volatile int java.lang.String.compareTo(java.lang.Object)