[nullsafe] Remove a wrong model for com.google.common.collect.Iterables.getFirst()
[nullsafe] Remove a wrong model for com.google.common.collect.Iterables.getFirst()

Summary:
1. The return value is annotated as Nullable in codebase
2. The second parameter can be null as well.

Reviewed By: artempyanykh

Differential Revision: D20766243

fbshipit-source-id: 9aad37a8c

facebook/infer,jvillard/infer,facebook/infer,jvillard/infer,jvillard/infer,jvillard/infer,jvillard/infer,facebook/infer,jvillard/infer,facebook/infer,facebook/infer,facebook/infer,facebook/infer,jvillard/infer