Has anyone successfullly used SaveAssetsProcessor?

I can't seem to hook into this: SaveAssetsProcessor. The documentation is severely lacking, as in not even listing a return value.

I have the following code as a start, but can't seem to get anything to happen ever...

using UnityEngine;
using UnityEditor;
using System.Collections;

public class FileModificationWarning : SaveAssetsProcessor {

    string[] OnWillSaveAssets (string[] paths) {
        Debug.Log("OnWillSaveAssets");
        foreach(string path in paths)
        Debug.Log(path);
        return paths;
    }
}

I've tried having OnWillSaveAssets be void as well, but no luck and no errors to indicate what could possibly be wrong.

Solved it. The function needs to be static:

using UnityEngine;
using UnityEditor;
using System.Collections;

public class FileModificationWarning : SaveAssetsProcessor {

    static string[] OnWillSaveAssets (string[] paths) {
        Debug.Log("OnWillSaveAssets");
        foreach(string path in paths)
        Debug.Log(path);
        return paths;
    }
}