Make JavaDoc tool happy by adding missing @return tag

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/lang/trunk@1654142 13f79535-47bb-0310-9956-ffa450edef68

src/main/java/org/apache/commons/lang3/builder/MultilineRecursiveToStringStyle.java

@@ -100,9 +100,10 @@ private void resetIndent() {
     }
 
     /**
-     * Creates a string(buffer) responsible for the indenting.
+     * Creates a StringBuilder responsible for the indenting.
+     * 
      * @param spaces how far to indent
-     * @return
+     * @return a StringBuilder with {spaces} leading space characters.
      */
     private StringBuilder spacer(int spaces) {
         StringBuilder sb = new StringBuilder();