Replaced deprecated `StringUtils` methods with suggested ones from `Strings.CS`

[StefanSpieker]

Replaced deprecated StringUtils methods with suggested ones from Strings.CS and removed an unused import while I was here.

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[StefanSpieker]

Hmm, it seems I would have to add commons-lang3 to all modules, not sure if that is intended. What do you think?

[timja]

Weird aren't you just added it to places commons-lang3 was already used?