Is guava's ImmutableXXX really immutable?

Question

I have been using guava for some time now and truly trusted it, until I stumbled of an example yesterday, which got me thinking. Long story short, here it is:

Answer 1

You mix the immutability of the list and the immutability of the objects it contains. In an immutable collection you cannot add/remove objects, but if the object it contains are mutable you can modify them after get()ing them.