Minor cleanup

Author: alextwoods

core/http-auth-aws/src/main/java/software/amazon/awssdk/http/auth/aws/internal/signer/V4CanonicalRequest.java

@@ -209,9 +209,8 @@ public static String getSignedHeadersString(List<Pair<String, List<String>>> can
             headersString.append(header.left()).append(';');
         }
 
-        int len = headersString.length();
-        if (len > 0) {
-            headersString.setLength(len - 1); // remove last semicolon
+        if (headersString.length() > 0) {
+            headersString.setLength(headersString.length() - 1); // remove last semicolon
         }
 
         return headersString.toString();