add test: NackHeaderTest

src/main/java/component/NackHeader.java

@@ -12,6 +12,10 @@ import encoding.*;
 public class NackHeader implements TlvComponentBase,InitialAble, IEncodingAble {
     // 变量
     private long nackReason;
+    // NackReason 定义
+    public static final long NackReasonUnknown  = 0;
+    public static final long NackReasonDuplicate= 1;
+    public static final long NackReasonNoRoute  = 2;
 
     // 函数
     public long getNackReason() {