I am new to Commons Exec, so this could also be an error in usage, but...
When I use the CommandLine class to add a argument that contains spaces, some quotes are added and are then part of the argument that is given.
For example: When I call java "what version" I get java.lang.NoClassDefFoundError: what version, and when I call java "\"what version\"" (which contains escaped quotes, that are part of the command line argument itself), I get java.lang.NoClassDefFoundError: "what version".
So the following test fails, because as you can see in the last line, Apache Exec is producing the latter version where it should have produced the first version:
Note that the same test passes if the space is removed from the argument. Please also note, that I am not trying to start an external Java process, but this is merely an example that I assume will work on every developers machine.