Review

class ExceptionUtils {
    /**
     * <p>Introspects the <code>Throwable</code> to obtain the root cause.</p>
     *
     * <p>This method walks through the exception chain to the last element,
     * "root" of the tree, using {@link #getCause(Throwable)}, and
     * returns that exception.</p>
     *
     * <p>From version 2.2, this method handles recursive cause structures
     * that might otherwise cause infinite loops. If the throwable parameter
     * has a cause of itself, then null will be returned. If the throwable
     * parameter cause chain loops, the last element in the chain before the
     * loop is returned.</p>
     *
     * @param throwable  the throwable to get the root cause for, may be null
     * @return the root cause of the <code>Throwable</code>,
     *  <code>null</code> if none found or null throwable input
     */
    public static Throwable getRootCause(Throwable throwable) {
        List list = getThrowableList(throwable);
        return (list.size() < 2 ? null : (Throwable)list.get(list.size() - 1));
    }

}