@Cacheable key generation questions

Hi

I am using the new @Cacheable annotation with keys defined via SpEL.
@Cacheable(value="oftenUpdatedCache", key="'relationList' + #p0 + #p1")

a) In order to be able to supply an eviction key I need to know how are my keys resolved if they are null?
b) Are the key values which are null simply dropped or replaced with some null place holder?
c) How are int values compared to String values used for building the key if I supply them via SpEL as above?
d) Are the int values converted to String and simply joined as a large string key?

If you do not know one of the answers but could point me in the right direction to check it in the source code this would be good too.