Use public getter to retrieve name from JarFile

ZipFile provides a public getter 'getName()' hence there is no need to
use reflection to access its private member 'name'.

Change-Id: If622fce7f902cc65483d66b834aff2c585b645e2
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
diff --git a/gerrit-launcher/src/main/java/com/google/gerrit/launcher/GerritLauncher.java b/gerrit-launcher/src/main/java/com/google/gerrit/launcher/GerritLauncher.java
index ef87395..33a3534 100644
--- a/gerrit-launcher/src/main/java/com/google/gerrit/launcher/GerritLauncher.java
+++ b/gerrit-launcher/src/main/java/com/google/gerrit/launcher/GerritLauncher.java
@@ -22,7 +22,6 @@
 import java.io.FileOutputStream;
 import java.io.IOException;
 import java.io.InputStream;
-import java.lang.reflect.Field;
 import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
 import java.lang.reflect.Modifier;
@@ -324,11 +323,8 @@
     // ZipFile may have the path of our JAR hiding within itself.
     //
     try {
-      Field nameField = ZipFile.class.getDeclaredField("name");
-      nameField.setAccessible(true);
-
       JarFile jar = ((JarURLConnection) myClazz.openConnection()).getJarFile();
-      File path = new File((String) nameField.get(jar));
+      File path = new File(jar.getName());
       if (path.isFile()) {
         return path;
       }