refactor: make createTempLibraryFile package-private and simplify test

Author: dyrpsf

src/main/java/com/uber/h3core/H3CoreLoader.java

@@ -93,7 +93,7 @@ public static NativeMethods loadNatives() throws IOException {
     return loadNatives(os, arch);
   }
 
-  private static File createTempLibraryFile(OperatingSystem os) throws IOException {
+  static File createTempLibraryFile(OperatingSystem os) throws IOException {
     // Check if the user specified a custom directory for native libraries
     String customDir = System.getProperty("h3.native.dir");
     File dir = customDir != null ? new File(customDir) : null;

src/test/java/com/uber/h3core/TestH3CoreLoader.java

@@ -78,12 +78,8 @@ void testCustomNativeDir() throws Exception {
       H3CoreLoader.OperatingSystem currentOs =
           H3CoreLoader.detectOs(System.getProperty("java.vendor"), System.getProperty("os.name"));
 
-      java.lang.reflect.Method method =
-          H3CoreLoader.class.getDeclaredMethod(
-              "createTempLibraryFile", H3CoreLoader.OperatingSystem.class);
-      method.setAccessible(true);
-
-      File tempFile = (File) method.invoke(null, currentOs);
+      // Call the package-private method directly! No reflection needed.
+      File tempFile = H3CoreLoader.createTempLibraryFile(currentOs);
 
       org.junit.jupiter.api.Assertions.assertTrue(
           tempFile.getAbsolutePath().startsWith(new File(customDir).getAbsolutePath()),