explicitly set plugin versions

Author: Stephen Powis

pom.xml

@@ -316,6 +316,7 @@
                     <plugin>
                         <groupId>org.apache.maven.plugins</groupId>
                         <artifactId>maven-source-plugin</artifactId>
+                        <version>3.0.1</version>
                         <executions>
                             <execution>
                                 <id>attach-sources</id>
@@ -330,6 +331,7 @@
                     <plugin>
                         <groupId>org.apache.maven.plugins</groupId>
                         <artifactId>maven-javadoc-plugin</artifactId>
+                        <version>3.0.1</version>
                         <executions>
                             <execution>
                                 <id>attach-javadocs</id>