title: Android Studio R8 NullPointerException
body: <p>When I update to <code>classpath 'com.android.tools.build:gradle:3.6.1'</code> I run into this non-understandable error.</p>
  
  <pre><code>R8: The method `java.util.concurrent.Flow$Subscriber org.reactivestreams.FlowAdapters.toFlowSubscriber(org.reactivestreams.Subscriber)` does not type check and will be assumed to be unreachable.
  R8: The method `java.util.concurrent.Flow$Processor org.reactivestreams.FlowAdapters.toFlowProcessor(org.reactivestreams.Processor)` does not type check and will be assumed to be unreachable.
  R8: The method `java.util.concurrent.Flow$Publisher org.reactivestreams.FlowAdapters.toFlowPublisher(org.reactivestreams.Publisher)` does not type check and will be assumed to be unreachable.
  
  &gt; Task :MXApp:minifyAdminReleaseWithR8 FAILED
  
  FAILURE: Build failed with an exception.
  
  * What went wrong:
  Execution failed for task ':MXApp:minifyAdminReleaseWithR8'.
  &gt; java.lang.NullPointerException (no error message)
  
  * Try:
  Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.
  
  * Get more help at https://help.gradle.org
  
  BUILD FAILED in 2m 9s
  </code></pre>
  
  <p>Maybe someone has a hint for me to get rid of it ?</p>