upgrade Maven plugins
diff --git a/pom.xml b/pom.xml
index 53c9d9c..46d5e4b 100644
--- a/pom.xml
+++ b/pom.xml
@@ -221,7 +221,7 @@
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-compiler-plugin</artifactId>
-        <version>2.3.2</version>
+        <version>3.7.0</version>
         <configuration>
           <source>${maven.compile.source}</source>
           <target>${maven.compile.target}</target>
@@ -251,7 +251,7 @@
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-jar-plugin</artifactId>
-        <version>2.3.1</version>
+        <version>3.1.0</version>
         <configuration>
           <archive>
             <compress>true</compress>
@@ -262,7 +262,7 @@
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-clean-plugin</artifactId>
-        <version>2.4.1</version>
+        <version>3.1.0</version>
       </plugin>
       <plugin>
         <artifactId>maven-assembly-plugin</artifactId>
@@ -310,7 +310,7 @@
         <plugin>
           <groupId>org.apache.maven.plugins</groupId>
           <artifactId>maven-surefire-plugin</artifactId>
-          <version>2.13</version>
+          <version>2.21.0</version>
         </plugin>
       </plugins>
     </pluginManagement>