LUCENE-10213: Use unicode escapes in message property files in Luke (remove hacks)

lucene/luke/build.gradle

@@ -57,6 +57,13 @@ tasks.withType(Jar) {
   }
 }
 
+// Process UTF8 property files to unicode escapes.
+tasks.withType(ProcessResources).configureEach { task ->
+  task.filesMatching("**/messages*.properties", {
+    filteringCharset = 'UTF-8'
+    filter(EscapeUnicode)
+  })
+}
 
 // Configure "stand-alone" JAR with proper dependency classpath links.
 task standaloneJar(type: Jar) {

lucene/luke/src/distribution/README.md

@@ -20,6 +20,14 @@
 This is Luke, Apache Lucene low-level index inspection and repair utility.
 
 Luke requires Java ${required.java.version}. You can start it with:
+```
 java -jar ${luke.cmd}
+```
+
+or, using Java modules:
+
+```
+java --module-path . --add-modules org.apache.logging.log4j --module lucene.luke
+```
 
 Happy index hacking!

lucene/luke/src/java/org/apache/lucene/luke/app/desktop/util/MessageUtils.java

@@ -17,13 +17,8 @@
 
 package org.apache.lucene.luke.app.desktop.util;
 
-import java.io.IOException;
-import java.io.InputStream;
-import java.io.InputStreamReader;
-import java.nio.charset.StandardCharsets;
 import java.text.MessageFormat;
 import java.util.Locale;
-import java.util.PropertyResourceBundle;
 import java.util.ResourceBundle;
 
 /** Utilities for accessing message resources. */
@@ -41,33 +36,8 @@ public class MessageUtils {
     return new MessageFormat(pattern, Locale.ENGLISH).format(args);
   }
 
-  // https://stackoverflow.com/questions/4659929/how-to-use-utf-8-in-resource-properties-with-resourcebundle
+  private static ResourceBundle bundle =
-  private static ResourceBundle.Control UTF8_RESOURCEBUNDLE_CONTROL =
+      ResourceBundle.getBundle(MESSAGE_BUNDLE_BASENAME, Locale.ENGLISH);
-      new ResourceBundle.Control() {
-        @Override
-        public ResourceBundle newBundle(
-            String baseName, Locale locale, String format, ClassLoader loader, boolean reload)
-            throws IllegalAccessException, InstantiationException, IOException {
-          String bundleName = toBundleName(baseName, locale);
-          String resourceName = toResourceName(bundleName, "properties");
-          try (InputStream is = loader.getResourceAsStream(resourceName)) {
-            return new PropertyResourceBundle(new InputStreamReader(is, StandardCharsets.UTF_8));
-          }
-        }
-      };
-
-  private static ResourceBundle bundle;
-
-  static {
-    Class<?> self = MessageUtils.class;
-    if (self.getModule().isNamed()) {
-      bundle = ResourceBundle.getBundle(MESSAGE_BUNDLE_BASENAME, Locale.ENGLISH, self.getModule());
-    } else {
-      bundle =
-          ResourceBundle.getBundle(
-              MESSAGE_BUNDLE_BASENAME, Locale.ENGLISH, UTF8_RESOURCEBUNDLE_CONTROL);
-    }
-  }
 
   private MessageUtils() {}
 }

lucene/luke/src/resources/org/apache/lucene/luke/app/desktop/messages/messages.properties

@@ -15,6 +15,9 @@
 # limitations under the License.
 #
 
+# This file must use UTF8 encoding. UTF8 is replaced with unicode
+# escapes at build time.
+
 # Common
 label.status=Status:
 label.help=Help