Compatibility fix with JDK9+

.travis.yml

@@ -1,10 +1,13 @@
 language: java
 jdk:
   - openjdk8
+  - openjdk11
 before_cache:
   - rm -f  $HOME/.gradle/caches/modules-2/modules-2.lock
   - rm -fr $HOME/.gradle/caches/*/plugin-resolution/
 cache:
   directories:
     - $HOME/.gradle/caches/
     - $HOME/.gradle/wrapper/
+script:
+  - ./gradlew --info

dynatest-engine/src/main/kotlin/com/github/mvysny/dynatest/engine/Utils.kt

@@ -16,13 +16,14 @@ internal val isRunningInsideGradle: Boolean get() {
             val jars: List<URL> = classLoader.urLs.toList()
             return (jars.any { it.toString().contains("gradle-worker.jar") })
         }
-        // JDK 9+ uses AppClassLoader
-        val methodGetUrls = classLoader::class.java.getDeclaredMethod("getURLs")
-        val jars = methodGetUrls.invoke(classLoader) as Array<URL>
-        return (jars.any { it.toString().contains("gradle-worker.jar") })
+        // JDK 9+ uses AppClassLoader which doesn't provide a list of URLs for us.
+        // we need to check in a different way whether there is `gradle-worker.jar` on the classpath.
+        // we know that it contains the worker/org/gradle/api/JavaVersion.class
+        val workerJar = classLoader.getResource("worker/org/gradle/api/JavaVersion.class")
+        return workerJar.toString().contains("gradle-worker.jar")
     } catch (t: Throwable) {
         // give up, just pretend that we're inside of Gradle
-        t.printStackTrace()
+        t.printStackTrace() // to see these stacktraces run Gradle with --info
         return true
     }
 }