Review

class ExceptionUtils {
    /**
     * <p>Adds to the list of method names used in the search for <code>Throwable</code>
     * objects.</p>
     * 
     * @param methodName  the methodName to add to the list, <code>null</code>
     *  and empty strings are ignored
     * @since 2.0
     */
    public static void addCauseMethodName(String methodName) {
        if (StringUtils.isNotEmpty(methodName) && !isCauseMethodName(methodName)) {            
            List list = getCauseMethodNameList();
            if (list.add(methodName)) {
                synchronized(CAUSE_METHOD_NAMES) {
                    CAUSE_METHOD_NAMES = toArray(list);
                }
            }
        }
    }

}