fix Javadoc generation (#116)

Author: sullis

.github/workflows/build.yml

@@ -30,4 +30,4 @@ jobs:
           restore-keys: ${{ runner.os }}-maven-
 
       - name: Build with Maven
-        run: mvn --no-transfer-progress --batch-mode -Dmaven.javadoc.skip=true verify
+        run: mvn --no-transfer-progress --batch-mode verify

pom.xml

@@ -145,6 +145,10 @@
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-javadoc-plugin</artifactId>
+                <configuration>
+                    <!-- needed to fix javadoc on java 11+ https://github.com/joel-costigliola/assertj-core/issues/1403 -->
+                    <source>8</source>
+                </configuration>
                 <executions>
                     <execution>
                         <id>attach-javadocs</id>