Upgrade to maven-javadoc-plugin 3.2.0

Closes gh-245

Author: philwebb

pom.xml

@@ -177,7 +177,7 @@
 				<plugin>
 					<groupId>org.apache.maven.plugins</groupId>
 					<artifactId>maven-javadoc-plugin</artifactId>
-					<version>3.1.0</version>
+					<version>3.2.0</version>
 				</plugin>
 				<plugin>
 					<groupId>org.apache.maven.plugins</groupId>