Sorry but that can't be the whole story. I have just checked on org.apache.commons.configuration.ConfigurationException and it does extend Exception so it will be caught by your try/catch . Are you compiling the code you think you are?
P.S. Rather then return an empty string if you get an exception (it would seem to me to be fatal) should you not your self throw an exceptions that wraps the one you are catching?
Retired horse trader.
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It appears that because of the missing library (Apache Commons Lang judging from the package name), the compiler sees that a ConfigurationException is thrown but it cannot see that it is an indirect sub class of Exception.
In an analogy, you can't tell who my grandfather is if you don't know who my father is. You may know my father's name because I told you, but that still doesn't tell you who his father is. You'll have to ask my father himself.