[nullsafe] Add models for FileChannel$MapMode
[nullsafe] Add models for FileChannel$MapMode

Summary: :

Reviewed By: mityal

Differential Revision: D27878084

fbshipit-source-id: f39d98b85

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