According to Findbugs, org.apache.velocity.context.InternalContextBase defines currentResource and eventCartridge as non-serializable, non-transient in a serializable class.
a) make Resource and EventCartridge serializable (might drag a large number of classes along)
b) remove Serializable from InternalContextBase (does the Context get serialized somewhere? Is it needed for e.g. Web Applications?)
c) make the fields transient, losing their contents after serialization / de-serialization.