Open java.base/java.lang for ALL-UNNAMED

Since jacoco 0.8.9 it does not open the java.lang package anymore,
so we need to do that on our own.

See "Agent should not open java.lang package to unnamed module of the application class loader"

jacoco/jacoco#1334

build.gradle

@@ -191,6 +191,10 @@ subprojects {
     //Required for building on Travis' container-based infrastructure to not be killed with
     //'exit code 137' - https://github.com/travis-ci/travis-ci/issues/5582
     jvmArgs '-Xmx512m'
+    jvmArgs(
+      //Required since jacoco does not do that anymore: Agent should not open java.lang package to unnamed module of the application class loader (https://github.com/jacoco/jacoco/pull/1334).
+      "--add-opens=java.base/java.lang=ALL-UNNAMED"
+    )
   }
 
   tasks.register("allDependencyInsight", DependencyInsightReportTask) {}