Can't invoke HashMap's getEntry via reflection on Java 8

I have some legacy code (compiled and ran successfully with JDK 7u55) similar to the following:

private static class MyHashMap extends HashMap {
    static Method getEntryMethod;

    static {
        try {
            getEntryMethod = HashMap.class.getDeclaredMethod("getEntry", Object.class);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

public static void main(String[] args) {
    MyHashMap myHashMap = new MyHashMap();
}

After trying to switch to JDK 8u31, it fails with:

java.lang.NoSuchMethodException: java.util.HashMap.getEntry(java.lang.Object)