keep-together.within-column

Hi,
I use the keep-together.within-column attribut for the fo:table-cell to have text wrapping. It's working fine with the text "https://www.xxxxxxxxxx.xxxxxxxxxxxxxxx.com/xxxxxxxx/services/MultiDiffusionWS" but it's not working with "com.xxxxxxxxxxxxx.xxxxxxx.xxxxxxx.xxxxxxxxx.GenericDecoder".
Could you help me to resolve this issue ?
Thanks in advance.