Temporarily reverting from JarFlinger to JarMerger to fix timestamp format in jars

Otherwise the resultant .jar files are considered to be illegal by java 9.

Bug: 144189353

Test: Run `./gradlew :documentfile:bundleLibCompileReleas && cd ../../ && zipinfo out/androidx/documentfile/build/intermediates/compile_library_classes/release/classes.jar` and notice that it says:

  Archive:  out/androidx/documentfile/build/intermediates/compile_library_classes/release/classes.jar
  Zip file size: 25291 bytes, number of entries: 6
  -rw----     2.0 fat     3515 bX defN 69-Dec-31 19:00 androidx/documentfile/provider/DocumentFile.class
  -rw----     2.0 fat     5626 bX defN 69-Dec-31 19:00 androidx/documentfile/provider/DocumentsContractApi19.class
  -rw----     2.0 fat     4975 bX defN 69-Dec-31 19:00 androidx/documentfile/provider/RawDocumentFile.class
  -rw----     2.0 fat     3279 bX defN 69-Dec-31 19:00 androidx/documentfile/provider/SingleDocumentFile.class
  -rw----     2.0 fat     6396 bX defN 69-Dec-31 19:00 androidx/documentfile/provider/TreeDocumentFile.class
  -rw----     2.0 fat      138 bX defN 69-Dec-31 19:00 androidx/documentfile/R.class
  6 files, 23929 bytes uncompressed, 23959 bytes compressed:  -0.1%

instead of

  Archive:  out/androidx/documentfile/build/intermediates/compile_library_classes/release/classes.jar
  Zip file size: 24989 bytes, number of entries: 6
  -rw----     0.0 fat     3279 b- stor 80-000-00 00:00 androidx/documentfile/provider/SingleDocumentFile.class
  -rw----     0.0 fat      138 b- defN 80-000-00 00:00 androidx/documentfile/R.class
  -rw----     0.0 fat     5626 b- stor 80-000-00 00:00 androidx/documentfile/provider/DocumentsContractApi19.class
  -rw----     0.0 fat     4975 b- stor 80-000-00 00:00 androidx/documentfile/provider/RawDocumentFile.class
  -rw----     0.0 fat     6396 b- stor 80-000-00 00:00 androidx/documentfile/provider/TreeDocumentFile.class
  -rw----     0.0 fat     3515 b- stor 80-000-00 00:00 androidx/documentfile/provider/DocumentFile.class
  6 files, 23929 bytes uncompressed, 23917 bytes compressed:  0.1%

Change-Id: I7e743e2650b1773dd33a04d111f4f5ec053ed1cf
diff --git a/gradle.properties b/gradle.properties
index 04c18ae..f3b3e79 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -10,3 +10,5 @@
 // Run multiple kotlin compilations in parallel within the same project.
 // See also https://github.com/JetBrains/kotlin/blob/1978db9d0e68a2ec29aded30a07e9c3c740c29f6/libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/plugin/KotlinProperties.kt#L100 and https://blog.jetbrains.com/kotlin/2019/01/kotlin-1-3-20-released/
 kotlin.parallel.tasks.in.project=true
+# TODO(b/144189353) : remove android.useNewJarCreator once it stops putting illegal timestamps into jars
+android.useNewJarCreator=false