add comment and test

hutool-core/src/main/java/cn/hutool/core/lang/UUID.java

@@ -119,12 +119,14 @@ public class UUID implements java.io.Serializable, Comparable<UUID> {
 	public static UUID randomUUID(boolean isSecure) {
 		final Random ng = isSecure ? Holder.numberGenerator : RandomUtil.getRandom();
 
-		byte[] randomBytes = new byte[16];
+		final byte[] randomBytes = new byte[16];
 		ng.nextBytes(randomBytes);
+
 		randomBytes[6] &= 0x0f; /* clear version */
 		randomBytes[6] |= 0x40; /* set to version 4 */
 		randomBytes[8] &= 0x3f; /* clear variant */
 		randomBytes[8] |= 0x80; /* set to IETF variant */
+
 		return new UUID(randomBytes);
 	}
 

hutool-core/src/main/java/cn/hutool/core/thread/SyncFinisher.java

@@ -16,9 +16,10 @@ import java.util.concurrent.ExecutorService;
  * ps:
  * //模拟1000个线程并发
  * SyncFinisher sf = new SyncFinisher(1000);
- * concurrencyTestUtil.run(() -> {
+ * sf.addWorker(() -> {
  *      // 需要并发测试的业务代码
  * });
+ * sf.start()
  * </pre>
  * 
  * 

hutool-core/src/test/java/cn/hutool/core/lang/UUIDTest.java

@@ -0,0 +1,21 @@
+package cn.hutool.core.lang;
+
+import cn.hutool.core.collection.ConcurrentHashSet;
+import cn.hutool.core.thread.ThreadUtil;
+import org.junit.Assert;
+import org.junit.Test;
+
+import java.util.Set;
+
+public class UUIDTest {
+
+	/**
+	 * 测试UUID是否存在重复问题
+	 */
+	@Test
+	public void fastUUIDTest(){
+		Set<String> set = new ConcurrentHashSet<>(100);
+		ThreadUtil.concurrencyTest(100, ()-> set.add(UUID.fastUUID().toString()));
+		Assert.assertEquals(100, set.size());
+	}
+}

hutool-core/src/test/java/cn/hutool/core/util/TypeUtilTest.java

@@ -56,4 +56,5 @@ public class TypeUtilTest {
 		public void service(String string) {
 		}
 	}
+
 }

hutool-crypto/src/main/java/cn/hutool/crypto/symmetric/SymmetricCrypto.java

@@ -204,7 +204,7 @@ public class SymmetricCrypto implements Serializable {
 			} else {
 				cipher.init(Cipher.ENCRYPT_MODE, secretKey, params);
 			}
-			return cipher.doFinal(paddingDataWithZero(data, cipher.getBlockSize()));
+				return cipher.doFinal(paddingDataWithZero(data, cipher.getBlockSize()));
 		} catch (Exception e) {
 			throw new CryptoException(e);
 		} finally {