Upgrade plugins

This fixes #1

Author: michael-o

pom.xml

@@ -340,12 +340,12 @@ limitations under the License.
         <plugin>
           <groupId>org.apache.maven.plugins</groupId>
           <artifactId>maven-clean-plugin</artifactId>
-          <version>2.6.1</version>
+          <version>3.0.0</version>
         </plugin>
         <plugin>
           <groupId>org.apache.maven.plugins</groupId>
           <artifactId>maven-compiler-plugin</artifactId>
-          <version>3.3</version>
+          <version>3.5.1</version>
           <configuration>
             <source>${maven.compiler.source}</source>
             <target>${maven.compiler.target}</target>
@@ -369,27 +369,27 @@ limitations under the License.
         <plugin>
           <groupId>org.apache.maven.plugins</groupId>
           <artifactId>maven-jar-plugin</artifactId>
-          <version>2.5</version>
+          <version>3.0.2</version>
         </plugin>
         <plugin>
           <groupId>org.apache.maven.plugins</groupId>
           <artifactId>maven-javadoc-plugin</artifactId>
-          <version>2.10.1</version>
+          <version>2.10.4</version>
         </plugin>
         <plugin>
           <groupId>org.apache.maven.plugins</groupId>
           <artifactId>maven-plugin-plugin</artifactId>
-          <version>3.4</version>
+          <version>3.5</version>
         </plugin>
         <plugin>
           <groupId>org.apache.maven.plugins</groupId>
           <artifactId>maven-project-info-reports-plugin</artifactId>
-          <version>2.8.1</version>
+          <version>2.9</version>
         </plugin>
         <plugin>
           <groupId>org.apache.maven.plugins</groupId>
           <artifactId>maven-release-plugin</artifactId>
-          <version>2.5.1</version>
+          <version>2.5.3</version>
           <configuration>
             <goals>deploy</goals>
             <mavenExecutorId>forked-path</mavenExecutorId>
@@ -400,7 +400,7 @@ limitations under the License.
         <plugin>
           <groupId>org.apache.maven.plugins</groupId>
           <artifactId>maven-resources-plugin</artifactId>
-          <version>2.7</version>
+          <version>3.0.2</version>
         </plugin>
         <plugin>
           <groupId>org.apache.maven.plugins</groupId>
@@ -415,25 +415,25 @@ limitations under the License.
         <plugin>
           <groupId>org.apache.maven.plugins</groupId>
           <artifactId>maven-site-plugin</artifactId>
-          <version>3.4</version>
+          <version>3.6</version>
           <configuration>
             <skipDeploy>true</skipDeploy><!-- don't deploy site with maven-site-plugin -->
           </configuration>
         </plugin>
         <plugin>
           <groupId>org.apache.maven.plugins</groupId>
           <artifactId>maven-source-plugin</artifactId>
-          <version>2.4</version>
+          <version>3.0.1</version>
         </plugin>
         <plugin>
           <groupId>org.apache.maven.plugins</groupId>
           <artifactId>maven-surefire-plugin</artifactId>
-          <version>2.18.1</version>
+          <version>2.20</version>
         </plugin>
         <plugin>
           <groupId>org.codehaus.plexus</groupId>
           <artifactId>plexus-component-metadata</artifactId>
-          <version>1.6</version>
+          <version>1.7.1</version>
           <executions>
             <execution>
               <id>process-classes</id>
@@ -454,6 +454,7 @@ limitations under the License.
     <plugins>
       <plugin>
         <artifactId>maven-enforcer-plugin</artifactId>
+          <version>1.4.1</version>
         <executions>
           <execution>
             <id>enforce-maven</id>
@@ -490,7 +491,7 @@ limitations under the License.
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-project-info-reports-plugin</artifactId>
-        <version>2.8.1</version><!-- TODO remove version once parent does not hardcode it -->
+        <version>2.9</version><!-- TODO remove version once parent does not hardcode it -->
         <reportSets>
           <reportSet>
             <reports>
@@ -529,12 +530,12 @@ limitations under the License.
           <plugin>
             <groupId>org.apache.maven.plugins</groupId>
             <artifactId>maven-surefire-report-plugin</artifactId>
-            <version>2.18.1</version>
+            <version>2.20</version>
           </plugin>
           <plugin>
             <groupId>org.apache.maven.plugins</groupId>
             <artifactId>maven-checkstyle-plugin</artifactId>
-            <version>2.13</version>
+            <version>2.17</version>
             <configuration>
               <configLocation>config/maven_checks.xml</configLocation>
               <headerLocation>https://raw.github.com/codehaus-plexus/plexus-pom/master/src/main/resources/config/plexus-header.txt</headerLocation>
@@ -551,7 +552,7 @@ limitations under the License.
           <plugin>
             <groupId>org.apache.maven.plugins</groupId>
             <artifactId>maven-pmd-plugin</artifactId>
-            <version>3.2</version>
+            <version>3.8</version>
             <configuration>
               <targetJdk>${maven.compiler.source}</targetJdk>
               <rulesets>
@@ -566,7 +567,7 @@ limitations under the License.
           <plugin>
             <groupId>org.codehaus.mojo</groupId>
             <artifactId>findbugs-maven-plugin</artifactId>
-            <version>3.0.2</version>
+            <version>3.0.4</version>
           </plugin>
           <plugin>
             <groupId>org.codehaus.mojo</groupId>
@@ -609,7 +610,7 @@ limitations under the License.
           <plugin>
             <groupId>org.codehaus.mojo</groupId>
             <artifactId>cobertura-maven-plugin</artifactId>
-            <version>2.6</version>
+            <version>2.7</version>
           </plugin>
         </plugins>
       </reporting>
@@ -621,6 +622,7 @@ limitations under the License.
           <plugin>
             <groupId>org.apache.maven.plugins</groupId>
             <artifactId>maven-gpg-plugin</artifactId>
+            <version>1.6</version>
             <configuration>
               <passphrase>${gpg.passphrase}</passphrase>
             </configuration>