Revert "Export implementation class jars for java_boot_libs"

This reverts commit 22ff0aaf51bdd9409eafe74151decb58f47308bc.

The workaround to support hidden API generation with prebuilts by
passing the full implementation jars through to the SDK snapshot is no
longer needed as the monolithic hidden API flag generation uses the
prebuilt flag files that are already part of the snapshot.

This change reverts that previous workaround.

Bug: 192868581
Test: - Update the prebuilts
      DIST_DIR=$PWD/dist TARGET_BUILD_VARIANT=userdebug art/build/build-art-module.sh --skip-apex
      packages/modules/ArtPrebuilt/update-art-module-prebuilts.py --local-dist=dist --skip-cls --skip-apex
      - Build hidden API flags to make sure it does not fail
Change-Id: Idb3fde6f7dcb171677316d8794a4af91ede1f7e0
diff --git a/android/sdk.go b/android/sdk.go
index e700031..da740f3 100644
--- a/android/sdk.go
+++ b/android/sdk.go
@@ -239,6 +239,12 @@
 	// to the zip
 	CopyToSnapshot(src Path, dest string)
 
+	// Return the path to an empty file.
+	//
+	// This can be used by sdk member types that need to create an empty file in the snapshot, simply
+	// pass the value returned from this to the CopyToSnapshot() method.
+	EmptyFile() Path
+
 	// Unzip the supplied zip into the snapshot relative directory destDir.
 	UnzipToSnapshot(zipPath Path, destDir string)