Summary:
Remove warning `'variant.getJavaCompile()' is obsolete and has been replaced with 'variant.getJavaCompileProvider()'.`
## Changelog
- swithed from `variant.getJavaCompile()` to `variant.getJavaCompileProvider()`
Pull Request resolved: https://github.com/facebook/flipper/pull/1168
Test Plan: n/a
Reviewed By: passy
Differential Revision: D21618883
Pulled By: cekkaewnumchai
fbshipit-source-id: 522fe5847b074836cc36a9e1b9a0487b044cf555