Minor cleanup of task Properties.expandText()

Fix a typo in the comment, and allocate the StringBuffer slightly later
in case it might not be needed.

Change-Id: Ib5f31d3f7bf6b5a1b2a1a33cf6060d5a86d967fa

src/main/java/com/googlesource/gerrit/plugins/task/Properties.java

diff --git a/src/main/java/com/googlesource/gerrit/plugins/task/Properties.java b/src/main/java/com/googlesource/gerrit/plugins/task/Properties.java
index 3568eb8..49cd4cf 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/task/Properties.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/task/Properties.java
@@ -323,18 +323,18 @@
     }
 
     /**
-     * Expand all properties (${property_name} -> property_value) in the given text . Returns same
+     * Expand all properties (${property_name} -> property_value) in the given text. Returns same
      * object if no expansions occured.
      */
     public String expandText(String text) {
       if (text == null) {
         return null;
       }
-      StringBuffer out = new StringBuffer();
       Matcher m = PATTERN.matcher(text);
       if (!m.find()) {
         return text;
       }
+      StringBuffer out = new StringBuffer();
       do {
         m.appendReplacement(out, Matcher.quoteReplacement(getValueForName(m.group(1))));
       } while (m.find());