Replace deprecated FileUtils with nio

Grappa deprecated FileUtils in favor of using nio directly. Hence, we
switch to nio.

Change-Id: Iec43a511835edf77878f3811c915705b2a5e8e38

BUCK

diff --git a/BUCK b/BUCK
index 581deae..1bbb56a 100644
--- a/BUCK
+++ b/BUCK
@@ -6,9 +6,6 @@
   '//lib/guice:guice',
   '//lib/jgit:jgit',
   '//lib/log:api',
-  '//lib:grappa', # used for it's parboiled part. See
-  # core's 0db7612e092b37c6ea04883a5a45f51c6d9ae433
-  # for details
   '//lib:velocity',
 ]
 

src/main/java/com/googlesource/gerrit/plugins/its/base/workflow/action/AddVelocityComment.java

diff --git a/src/main/java/com/googlesource/gerrit/plugins/its/base/workflow/action/AddVelocityComment.java b/src/main/java/com/googlesource/gerrit/plugins/its/base/workflow/action/AddVelocityComment.java
index d8e3b59..f3a1cc2 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/its/base/workflow/action/AddVelocityComment.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/its/base/workflow/action/AddVelocityComment.java
@@ -25,13 +25,13 @@
 import org.apache.commons.lang.StringUtils;
 import org.apache.velocity.VelocityContext;
 import org.apache.velocity.runtime.RuntimeInstance;
-import org.parboiled.common.FileUtils;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 import java.io.File;
 import java.io.IOException;
 import java.io.StringWriter;
+import java.nio.file.Files;
 import java.nio.file.Path;
 import java.util.Arrays;
 import java.util.Set;
@@ -105,12 +105,12 @@
       if (templateName.isEmpty()) {
         log.error("No template name given in " + actionRequest);
       } else {
-        File templateFile = new File(sitePath.toFile(), ITS_TEMPLATE_DIR +
-            File.separator + templateName + ".vm");
-        if (templateFile.canRead()) {
-          template = FileUtils.readAllText(templateFile);
+        Path templateDir = sitePath.resolve(ITS_TEMPLATE_DIR);
+        Path templatePath = templateDir.resolve(templateName + ".vm");
+        if (Files.isReadable(templatePath)) {
+          template = new String(Files.readAllBytes(templatePath));
         } else {
-          log.error("Cannot read template " + templateFile);
+          log.error("Cannot read template " + templatePath);
         }
       }
     }