Consistently use character encoding constants

Use the java.nio.charset.StandardCharsets.{ISO_8859_1,UTF_8} constants'
name() methods instead of hard-coding the strings.

Where possible, use method variants that take a Charset rather than
a String. This removes the need to catch UnsupportedEncodingException
in some cases.

Change-Id: I4ac1ba0a753de715e1f38ce631842f527b9e127c

gerrit-server/src/main/java/com/google/gerrit/server/documentation/MarkdownFormatter.java

@@ -14,6 +14,7 @@
 
 package com.google.gerrit.server.documentation;
 
+import static java.nio.charset.StandardCharsets.UTF_8;
 import static org.pegdown.Extensions.ALL;
 import static org.pegdown.Extensions.HARDWRAPS;
 import static org.pegdown.Extensions.SUPPRESS_ALL_HTML;
@@ -159,7 +160,7 @@ public class MarkdownFormatter {
     try (InputStream in = url.openStream();
         TemporaryBuffer.Heap tmp = new TemporaryBuffer.Heap(128 * 1024)) {
       tmp.copy(in);
-      return new String(tmp.toByteArray(), "UTF-8");
+      return new String(tmp.toByteArray(), UTF_8);
     }
   }
 }