fix HttpServletRequestUtils

@@ -25,7 +25,7 @@ public class HttpServletRequestUtils {
 			StringBuilder paramStringBuilder = new StringBuilder();
 			for (Map.Entry<String, String[]> entry : request.getParameterMap().entrySet()) {
 				String value = ArrayUtils.isEmpty(entry.getValue()) ? null : entry.getValue()[0];
-				paramStringBuilder.append("&").append(entry.getKey()).append("=").append(value);
+				paramStringBuilder.append('&').append(entry.getKey()).append('=').append(value);
 			}
 			return paramStringBuilder.toString().replaceFirst("&", "");
 		}
@@ -59,7 +59,7 @@ public class HttpServletRequestUtils {
 		StringBuilder paramStringBuilder = new StringBuilder();
 		for (Map.Entry<String, String> entry : paramMap.entrySet()) {
 			String key = entry.getKey();
-			paramStringBuilder.append("&").append(key).append("=").append(entry.getValue());
+			paramStringBuilder.append('&').append(key).append('=').append(entry.getValue());
 		}
 		return paramStringBuilder.toString().replaceFirst("&", "");
 	}