This is what i found when i separately run
> Task :app:compileDebugJavaWithJavac
Putting task artifact state for task ':app:compileDebugJavaWithJavac' into context took 0.001 secs.
file or directory 'Z:\app\libs', not found
file or directory 'Z:\app\src\main\libs', not found
file or directory 'Z:\app\src\debug\java', not found
Executing task ':app:compileDebugJavaWithJavac' (up-to-date check took 0.095 secs) due to:
Task has failed previously.
All input files are considered out-of-date for incremental task ':app:compileDebugJavaWithJavac'.
Compiling with source level 1.7 and target level 1.7.
file or directory 'Z:\app\libs', not found
file or directory 'Z:\app\src\main\libs', not found
Creating new cache for classAnalysis, path Z:\.gradle\4.1\javaCompile\classAnalysis.bin, access org.gradle.cache.internal.DefaultCacheAccess@7dbe2fdc
Creating new cache for jarAnalysis, path Z:\.gradle\4.1\javaCompile\jarAnalysis.bin, access org.gradle.cache.internal.DefaultCacheAccess@7dbe2fdc
Creating new cache for taskJars, path Z:\.gradle\4.1\javaCompile askJars.bin, access org.gradle.cache.internal.DefaultCacheAccess@7dbe2fdc
Creating new cache for taskHistory, path Z:\.gradle\4.1\javaCompile askHistory.bin, access org.gradle.cache.internal.DefaultCacheAccess@7dbe2fdc
:app:compileDebugJavaWithJavac - is not incremental (e.g. outputs have changed, no previous execution, etc.).
file or directory 'Z:\app\src\debug\java', not found
Compiling with JDK Java compiler API.
Z:\app\src\main\java\com\epicgames\ue4\GameApplication.java:7: error: cannot find symbol
import android.arch.lifecycle.ProcessLifecycleOwner;
Seems like the Z directory is not there ! I’m sure I’m near to the solution now, but what is it ?