Bump maven-javadoc-plugin from 2.10.4 to 3.1.0

Bumps [maven-javadoc-plugin](https://github.com/apache/maven-javadoc-plugin) from 2.10.4 to 3.1.0.
- [Release notes](https://github.com/apache/maven-javadoc-plugin/releases)
- [Commits](apache/maven-javadoc-plugin@maven-javadoc-plugin-2.10.4...maven-javadoc-plugin-3.1.0)

Author: dependabot-preview[bot]

pom.xml

@@ -34,7 +34,7 @@
         <logback.version>1.2.3</logback.version>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
         <maven-source-plugin.version>3.0.1</maven-source-plugin.version>
-        <maven-javadoc-plugin.version>2.10.4</maven-javadoc-plugin.version>
+        <maven-javadoc-plugin.version>3.1.0</maven-javadoc-plugin.version>
         <maven-cobertura-plugin.version>2.7</maven-cobertura-plugin.version>
         <maven-coveralls-plugin.version>4.3.0</maven-coveralls-plugin.version>
         <maven-compiler-plugin.version>3.6.1</maven-compiler-plugin.version>