Specify charset to fix DefaultCharset error from error prone

When all error prone warnings are enabled the DefaultCharset
bug pattern is reported, for example:

  plugins/plugin-manager/src/main/java/com/googlesource/gerrit/plugins/manager/FirstWebLoginListener.java:56:
  error: [DefaultCharset] Implicit use of the platform default charset, which
  can result in differing behaviour between JVM executions or incorrect behavior
  if the encoding of the data source doesn't match expectations.
        Files.write(firstLoginFile, new Date().toString().getBytes(), StandardOpenOption.CREATE);
                                                                  ^
    (see https://errorprone.info/bugpattern/DefaultCharset)

Change-Id: I29e19b68c014da9afd491006d936f92219808978
diff --git a/src/main/java/com/googlesource/gerrit/plugins/manager/FirstWebLoginListener.java b/src/main/java/com/googlesource/gerrit/plugins/manager/FirstWebLoginListener.java
index 722d406..f0c934c 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/manager/FirstWebLoginListener.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/manager/FirstWebLoginListener.java
@@ -14,6 +14,8 @@
 
 package com.googlesource.gerrit.plugins.manager;
 
+import static java.nio.charset.StandardCharsets.UTF_8;
+
 import com.google.gerrit.extensions.annotations.PluginData;
 import com.google.gerrit.httpd.WebLoginListener;
 import com.google.gerrit.server.IdentifiedUser;
@@ -53,7 +55,8 @@
       if (!firstLoginFile.toFile().exists()) {
         response.sendRedirect(pluginUrlPath + "static/intro.html");
 
-        Files.write(firstLoginFile, new Date().toString().getBytes(), StandardOpenOption.CREATE);
+        Files.write(
+            firstLoginFile, new Date().toString().getBytes(UTF_8), StandardOpenOption.CREATE);
       }
     }
   }
diff --git a/src/main/java/com/googlesource/gerrit/plugins/manager/XAuthFilter.java b/src/main/java/com/googlesource/gerrit/plugins/manager/XAuthFilter.java
index de1eb10..616b9a4 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/manager/XAuthFilter.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/manager/XAuthFilter.java
@@ -14,6 +14,8 @@
 
 package com.googlesource.gerrit.plugins.manager;
 
+import static java.nio.charset.StandardCharsets.UTF_8;
+
 import com.google.gerrit.extensions.registration.DynamicItem;
 import com.google.gerrit.httpd.WebSession;
 import com.google.gerrit.server.AccessPath;
@@ -85,8 +87,8 @@
               return new TokenReplaceOutputStream(
                   (HttpServletResponse) getResponse(),
                   origContentLength,
-                  "@X-Gerrit-Auth".getBytes(),
-                  gerritAuth.getBytes());
+                  "@X-Gerrit-Auth".getBytes(UTF_8),
+                  gerritAuth.getBytes(UTF_8));
             }
           };
 
diff --git a/src/main/java/com/googlesource/gerrit/plugins/manager/gson/SmartGson.java b/src/main/java/com/googlesource/gerrit/plugins/manager/gson/SmartGson.java
index d26f829..ae339de 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/manager/gson/SmartGson.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/manager/gson/SmartGson.java
@@ -14,6 +14,8 @@
 
 package com.googlesource.gerrit.plugins.manager.gson;
 
+import static java.nio.charset.StandardCharsets.UTF_8;
+
 import com.google.gerrit.json.OutputFormat;
 import com.google.gson.Gson;
 import com.google.gson.JsonObject;
@@ -52,6 +54,6 @@
     } catch (MalformedURLException e) {
       throw new IllegalArgumentException("Internal error: Gerrit CI URL seems to be malformed", e);
     }
-    return new InputStreamReader(ciUrl.openStream());
+    return new InputStreamReader(ciUrl.openStream(), UTF_8);
   }
 }
diff --git a/src/main/java/com/googlesource/gerrit/plugins/manager/repository/JenkinsCiPluginsRepository.java b/src/main/java/com/googlesource/gerrit/plugins/manager/repository/JenkinsCiPluginsRepository.java
index 31f77e7..66c4c8d 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/manager/repository/JenkinsCiPluginsRepository.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/manager/repository/JenkinsCiPluginsRepository.java
@@ -14,6 +14,8 @@
 
 package com.googlesource.gerrit.plugins.manager.repository;
 
+import static java.nio.charset.StandardCharsets.UTF_8;
+
 import com.google.gson.JsonArray;
 import com.google.gson.JsonElement;
 import com.google.inject.Inject;
@@ -168,7 +170,8 @@
               "%s/artifact/%s",
               buildExecution.getString("url"), verArtifactJson.get().getString("relativePath"));
       try (BufferedReader reader =
-          new BufferedReader(new InputStreamReader(new URL(versionUrl).openStream()), 4096)) {
+          new BufferedReader(
+              new InputStreamReader(new URL(versionUrl).openStream(), UTF_8), 4096)) {
         String line;
         while ((line = reader.readLine()) != null) {
           if (artifactBody.length() > 0) {