[dev] add apache licence for quartz's CronExpression

powerjob-server/src/main/java/com/github/kfcfans/powerjob/server/common/utils/CronExpression.java

@@ -1,5 +1,19 @@
 package com.github.kfcfans.powerjob.server.common.utils;
+/*
+Copyright [2020] [KFCFans]
 
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+ */
 import java.io.Serializable;
 import java.text.ParseException;
 import java.util.Calendar;

powerjob-server/src/main/java/com/github/kfcfans/powerjob/server/common/utils/timewheel/HashedWheelTimer.java

@@ -37,8 +37,6 @@ public class HashedWheelTimer implements Timer {
 
     private final ExecutorService taskProcessPool;
 
-    private static final int MAXIMUM_CAPACITY = 1 << 30;
-
     public HashedWheelTimer(long tickDuration, int ticksPerWheel) {
         this(tickDuration, ticksPerWheel, 0);
     }

powerjob-server/src/main/java/com/github/kfcfans/powerjob/server/common/utils/timewheel/TimerFuture.java

@@ -1,7 +1,7 @@
 package com.github.kfcfans.powerjob.server.common.utils.timewheel;
 
 /**
- * description
+ * TimerFuture
  *
  * @author tjq
  * @since 2020/4/3