diff --git a/src/main/java/xyz/zhouxy/plusone/commons/util/IdGenerator.java b/src/main/java/xyz/zhouxy/plusone/commons/util/IdGenerator.java
index 9dc028b..cd72ac9 100644
--- a/src/main/java/xyz/zhouxy/plusone/commons/util/IdGenerator.java
+++ b/src/main/java/xyz/zhouxy/plusone/commons/util/IdGenerator.java
@@ -21,6 +21,8 @@ import java.util.Objects;
 import java.util.UUID;
 import java.util.concurrent.ConcurrentHashMap;
 
+import javax.annotation.Nonnull;
+
 /**
  * ID 生成器
  *
@@ -48,7 +50,7 @@ public class IdGenerator {
         return toSimpleString(UUID.randomUUID());
     }
 
-    public static String toSimpleString(UUID uuid) {
+    public static String toSimpleString(@Nonnull UUID uuid) {
         AssertTools.checkArgument(Objects.nonNull(uuid));
         return (uuidDigits(uuid.getMostSignificantBits() >> 32, 8) +
                 uuidDigits(uuid.getMostSignificantBits() >> 16, 4) +