function findInWorkingSet(fullPath) {
        DeprecationWarning.deprecationWarning("Use MainViewManager.findInWorkingSet() instead of DocumentManager.findInWorkingSet()", true);
        return MainViewManager.findInWorkingSet(MainViewManager.ACTIVE_PANE, fullPath);
    }
Returns the index of the file matching fullPath in the working set.
@deprecated Use MainViewManager.findInWorkingSet() instead
@param {!string} fullPath
@return {number} index, -1 if not found