Fix buildSrc:test failing on JDKs before JDK 25 with Non-English locale

buildSrc/src/test/java/org/springframework/build/multirelease/MultiReleaseJarPluginTests.java

@@ -43,10 +43,13 @@ public class MultiReleaseJarPluginTests {
 
 	private File buildFile;
 
+	private File propertiesFile;
+
 	@BeforeEach
 	void setup(@TempDir File projectDir) {
 		this.projectDir = projectDir;
 		this.buildFile = new File(this.projectDir, "build.gradle");
+		this.propertiesFile = new File(this.projectDir, "gradle.properties");
 	}
 
 	@Test
@@ -131,6 +134,9 @@ void validateJar() throws IOException {
 				}
 				multiRelease { releaseVersions 17 }
 				""");
+		writeGradleProperties("""
+				org.gradle.jvmargs=-Duser.language=en
+				""");
 		writeClass("src/main/java17", "Main.java", """
 				public class Main {
 
@@ -152,6 +158,12 @@ private void writeBuildFile(String buildContent) throws IOException {
 		}
 	}
 
+	private void writeGradleProperties(String properties) throws IOException {
+		try (PrintWriter out = new PrintWriter(new FileWriter(this.propertiesFile))) {
+			out.print(properties);
+		}
+	}
+
 	private void writeClass(String path, String fileName, String fileContent) throws IOException {
 		Path folder = this.projectDir.toPath().resolve(path);
 		Files.createDirectories(folder);