How would one obtain getType of CtInvocation which is a lambda expression?

For example,

`assertThrows(NullPointerException.class, () -> getPredicateInstance(new Predicate[] { null }));`

I want to obtain return type of `getPredicateInstance`

This function is an abstract function defined prior as shown here:
`protected abstract Predicate getPredicateInstance(Collection> predicates);`

Currently, it is returning `null`. I was wondering if there is any work around I can try?

Thank you so much,
Kim