Review

class BooleanUtils {
    /**
     * <p>Converts a Boolean to a String returning <code>'true'</code>,
     * <code>'false'</code>, or <code>null</code>.</p>
     * 
     * <pre>
     *   BooleanUtils.toStringTrueFalse(Boolean.TRUE)  = "true"
     *   BooleanUtils.toStringTrueFalse(Boolean.FALSE) = "false"
     *   BooleanUtils.toStringTrueFalse(null)          = null;
     * </pre>
     *
     * @param bool  the Boolean to check
     * @return <code>'true'</code>, <code>'false'</code>,
     *  or <code>null</code>
     */
    public static String toStringTrueFalse(Boolean bool) {
        return toString(bool, "true", "false", null);
    }

}