You may have problems if the class loader decides to load classes from a different version of the jar file than you expect. Such problems are usually difficult to track. The server will browse the banks in a specific order (in alphabetical order by file name?) And use the first corresponding class / resource that it finds. There is probably no guarantee that the first version of the jar file looks first.
I do not know any tools that would know which banks are not used. This may not be possible in the general case due to reflection, but a certain degree of automatic verification should be possible, at least theoretically.
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