Use UTF-8 to encode payload

HttpClient defaults to ISO-8859-1, but Gerrit gives us UTF-8, and
Phabricator expects UTF-8. So we pass along UTF-8 to avoid encoding
issues.

Change-Id: I443b183f9709c965bec12fa4194d8cab6e2f3616

src/main/java/com/googlesource/gerrit/plugins/its/phabricator/conduit/ConduitConnection.java

diff --git a/src/main/java/com/googlesource/gerrit/plugins/its/phabricator/conduit/ConduitConnection.java b/src/main/java/com/googlesource/gerrit/plugins/its/phabricator/conduit/ConduitConnection.java
index 72d343c..10644d1 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/its/phabricator/conduit/ConduitConnection.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/its/phabricator/conduit/ConduitConnection.java
@@ -31,6 +31,7 @@
 
 import java.io.IOException;
 import java.io.UnsupportedEncodingException;
+import java.nio.charset.StandardCharsets;
 import java.util.HashMap;
 import java.util.Map;
 
@@ -96,11 +97,7 @@
 
     log.trace("Calling phabricator method " + method
         + " with the parameters " + json );
-    try {
-      httppost.setEntity(new StringEntity("params=" + json));
-    } catch (UnsupportedEncodingException e) {
-      throw new ConduitException("Cannot encode parameters", e);
-    }
+    httppost.setEntity(new StringEntity("params=" + json, StandardCharsets.UTF_8));
 
     CloseableHttpResponse response;
     try {