This update backports changes from the commons-collections 3.2.2 release
which disable the deserialisation of the functors classes unless the
system property org.apache.commons.collections.enableUnsafeSerialization
is set to true. This fixes a vulnerability in unsafe applications
deserialising objects from untrusted sources without sanitising the
input data. Classes considered unsafe are: CloneTransformer, ForClosure,
InstantiateFactory, InstantiateTransformer, InvokerTransformer,
PrototypeCloneFactory, PrototypeSerializationFactory and WhileClosure.