Use mvnw.cmd and gradlew.bat on Windows

Also adds a Windows build.

.github/workflows/build-on-windows.yml

@@ -0,0 +1,26 @@
+name: Build on Windows
+on:
+  push:
+    branches:
+      - main
+  workflow_dispatch:
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+jobs:
+  build:
+    name: Build
+    runs-on: windows-latest
+    steps:
+      - name: Check out
+        uses: actions/checkout@v4
+
+      - name: Set up JDK 17
+        uses: actions/setup-java@v4
+        with:
+          java-version: '17'
+          distribution: 'liberica'
+          cache: 'maven'
+
+      - name: Build with Maven
+        run: ./mvnw --batch-mode --update-snapshots --no-transfer-progress verify

start-site/src/test/java/io/spring/start/site/ProjectGenerationIntegrationTests.java

@@ -44,6 +44,7 @@
 import io.spring.initializr.web.project.WebProjectRequest;
 import io.spring.start.testsupport.Homes;
 import io.spring.start.testsupport.TemporaryFiles;
+import org.apache.commons.lang3.SystemUtils;
 import org.junit.jupiter.api.TestInstance;
 import org.junit.jupiter.api.TestInstance.Lifecycle;
 import org.junit.jupiter.api.parallel.Execution;
@@ -163,17 +164,22 @@ private void releaseHome(BuildSystem buildSystem, Path home) {
 
 	private ProcessBuilder createProcessBuilder(BuildSystem buildSystem, Path home) {
 		if (buildSystem.id().equals(MavenBuildSystem.ID)) {
-			ProcessBuilder processBuilder = new ProcessBuilder("./mvnw",
+			ProcessBuilder processBuilder = new ProcessBuilder((isWindows()) ? "mvnw.cmd" : "./mvnw",
 					"-Dmaven.repo.local=" + home.resolve("repository").toFile(), "package");
 			processBuilder.environment().put("MAVEN_USER_HOME", home.toFile().getAbsolutePath());
 			return processBuilder;
 		}
 		if (buildSystem.id().equals(GradleBuildSystem.ID)) {
-			ProcessBuilder processBuilder = new ProcessBuilder("./gradlew", "--no-daemon", "build");
+			ProcessBuilder processBuilder = new ProcessBuilder((isWindows()) ? "gradlew.bat" : "./gradlew",
+					"--no-daemon", "build");
 			processBuilder.environment().put("GRADLE_USER_HOME", home.toFile().getAbsolutePath());
 			return processBuilder;
 		}
 		throw new IllegalStateException("Unknown build system '%s'".formatted(buildSystem.id()));
 	}
 
+	private boolean isWindows() {
+		return SystemUtils.IS_OS_WINDOWS;
+	}
+
 }