Android: call custom methods in a ContentProvider

I have a custom ContentProvider I use to store fixes obtained from the GPS into a SQLite database. This class overrides ContentProvider methods (delete, insert, query...), but notice I have also included a method to query the last fix.

public class FixesContentProvider extends ContentProvider {
    @Override
    public int delete(...) { ... }
    ...
    @Override
    public Cursor query(...) { ... }

    public Cursor getLastFix(Uri uri) { ... }
}

It is pretty easy to query data from other services or activities by calling getContentResolver().

ContentResolver cR = getContentResolver();
Cursor fixes = cR.query(CONTENT_URI, ...);

But I am not able to call my custom method (FixesContentProvider#getLastFix). How could I call custom methods defined in a ContentProvider?

Maybe I don't understand how ContentProviders/ContentResolvers work in this case, but official Android documentation provided by Google is not very clear in this sense.