Apply java plugin to buildSrc.
Apply java plugin to buildSrc.

Change-Id: I39e29b2d6ac5d23f4d6316503ad1c505856c1e10
Test: opened project in studio locally and nhow JDiffTask.java is no longer red.

androidx/androidx,androidx/androidx,AndroidX/androidx,aosp-mirror/platform_frameworks_support,aosp-mirror/platform_frameworks_support,androidx/androidx,AndroidX/androidx,AndroidX/androidx,AndroidX/androidx,androidx/androidx,AndroidX/androidx,androidx/androidx,AndroidX/androidx,aosp-mirror/platform_frameworks_support,androidx/androidx,androidx/androidx,AndroidX/androidx,AndroidX/androidx,aosp-mirror/platform_frameworks_support,androidx/androidx,androidx/androidx,aosp-mirror/platform_frameworks_support,androidx/androidx,AndroidX/androidx,AndroidX/androidx