Update sample to not have empty test sets

This is an error in Gradle 9

Author: jjohannes

samples/use-only-java-module-testing-plugin/app/build.gradle.kts

@@ -18,3 +18,7 @@ dependencies {
 
     runtimeOnly("org.slf4j:slf4j-simple")
 }
+
+javaModuleTesting.whitebox(testing.suites["test"]) {
+    requires.add("org.junit.jupiter.api")
+}

samples/use-only-java-module-testing-plugin/build-logic/src/main/kotlin/org.my.gradle.java-module.gradle.kts

@@ -4,15 +4,11 @@ plugins {
     id("org.gradlex.java-module-testing")
 }
 
-javaModuleTesting.whitebox(
-    testing.suites.getByName<JvmTestSuite>("test") {
-        useJUnitJupiter("")
-        targets.all {
-            testTask { jvmArgs("-Dorg.slf4j.simpleLogger.defaultLogLevel=error") }
-        }
+testing.suites.getByName<JvmTestSuite>("test") {
+    useJUnitJupiter("")
+    targets.all {
+        testTask { jvmArgs("-Dorg.slf4j.simpleLogger.defaultLogLevel=error") }
     }
-) {
-    requires.add("org.junit.jupiter.api")
 }
 
 testing.suites.create<JvmTestSuite>("integtest") {

samples/use-only-java-module-testing-plugin/lib/src/integtest/java/org/my/lib/integtest/LibIntegTest.java

@@ -0,0 +1,19 @@
+package org.my.lib.integtest;
+
+import org.junit.jupiter.api.Test;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+public class LibIntegTest {
+
+    @Test
+    public void libWorks() throws IOException {
+        // assertTrue(...);
+    }
+
+}