fix for javadoc bug

Author: Eugen Freiter

pom.xml

@@ -195,9 +195,10 @@
 			<plugin>
 				<groupId>org.apache.maven.plugins</groupId>
 				<artifactId>maven-javadoc-plugin</artifactId>
-				<version>3.0.1</version>
+				<version>3.2.0</version>
 				<configuration>
 					<excludePackageNames>io.github.hapjava.server.impl</excludePackageNames>
+					<source>8</source>
 				</configuration>
 				<executions>
 					<execution>