AccountInfo: Implement toString

This makes the output in debug logs and stack traces easier to read.

Change-Id: Ia463a5389b98962b5da8f749f29ec444b29b2736

java/com/google/gerrit/extensions/common/AccountInfo.java

@@ -14,6 +14,7 @@
 
 package com.google.gerrit.extensions.common;
 
+import com.google.common.base.MoreObjects;
 import java.util.List;
 import java.util.Objects;
 
@@ -54,6 +55,16 @@ public class AccountInfo {
     return false;
   }
 
+  @Override
+  public String toString() {
+    return MoreObjects.toStringHelper(this)
+        .add("id", _accountId)
+        .add("name", name)
+        .add("email", email)
+        .add("username", username)
+        .toString();
+  }
+
   @Override
   public int hashCode() {
     return Objects.hash(