Correction classe App

build.gradle

@@ -21,5 +21,5 @@ test {
 }
 
 application {
-    mainClassName = "Main"
+    mainClassName = "App"
 }
\ No newline at end of file

src/main/java/App.java

+public class App {
+  public static void main(String[] args){
+    // TODO add code
+  }
+}