public void setEmptyText(CharSequence text) {
        ensureContent();
        if (mEmptyView != null && mEmptyView instanceof TextView) {
            ((TextView) mEmptyView).setText(text);
        } else {
            throw new IllegalStateException("Can't be used with a custom content view");
        }
    }
The default content for a ProgressFragment has a TextView that can be shown when
the content is empty {@link #setContentEmpty(boolean)}.
If you would like to have it shown, call this method to supply the text it should use.

@param text Text for empty view
@see #setEmptyText(int)
progressfragment/src/com/devspark/progressfragment/ProgressFragment.java