Replace "UTF8" with StandardCharsets.UTF_8

Avoids NON-NLS and possible UnsupportedEncodingException

bundles/org.eclipse.osgi.tests/src/org/eclipse/osgi/tests/bundles/BundleInstallUpdateTests.java

@@ -27,6 +27,7 @@
 import java.lang.reflect.Method;
 import java.net.URL;
 import java.net.URLEncoder;
+import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
 import java.nio.file.StandardCopyOption;
 import java.util.Collections;
@@ -283,7 +284,7 @@ public void doTestSpaceCharsBundleEntry(char c) throws IOException, BundleExcept
  InputStream is = entryURL.openStream();
  is.close();
 
- String encodeEntry = URLEncoder.encode(entryName, "UTF-8");
+ String encodeEntry = URLEncoder.encode(entryName, StandardCharsets.UTF_8);
  String urlString = entryURL.toExternalForm();
  urlString = urlString.substring(0, urlString.indexOf(entryName)) + encodeEntry;
  URL encodedURL = new URL(urlString);