update string buffer to string builder.

Author: liuhongyuand

EasyRest/src/main/java/tech/dbgsoftware/easyrest/utils/ThreadStackUtils.java

@@ -4,7 +4,7 @@ public class ThreadStackUtils {
 
     public static String getStackInfo() {
         StringBuilder stringBuffer = new StringBuilder();
-        for (int i = Math.min(1, Thread.currentThread().getStackTrace().length); i < Math.min(18, Thread.currentThread().getStackTrace().length); i++) {
+        for (int i = Math.min(3, Thread.currentThread().getStackTrace().length); i < Math.min(18, Thread.currentThread().getStackTrace().length); i++) {
             String className = Thread.currentThread().getStackTrace()[i].getClassName();
             String methodName = Thread.currentThread().getStackTrace()[i].getMethodName();
             String line = String.valueOf(Thread.currentThread().getStackTrace()[i].getLineNumber());