[FLINK-36116] Update Javadoc plugin. This closes #25265

* [FLINK-36116] Update Javadoc plugin

The Javadoc needs to be updated since Javadoc generation fails with a failed cast (com.sun.tools.javadoc.ClassDocImpl cannot be cast to com.sun.javadoc.AnnotationTypeDoc)

* [FLINK-36116] Make Javadoc generation fail on errors

Failing to generate Javadocs should fail the documentation build, to avoid that this issue goes undetected for a long period of time.

(cherry picked from commit 2ca359a)

.github/workflows/docs.sh

@@ -53,8 +53,7 @@ mvn clean install -B -DskipTests -Dfast -Pskip-webui-build
 # build java/scala docs
 mkdir -p docs/target/api
 mvn javadoc:aggregate -B \
-    -DadditionalJOption="-Xdoclint:none --allow-script-in-comments" \
-    -Dmaven.javadoc.failOnError=false \
+    -Dmaven.javadoc.failOnError=true \
     -Dcheckstyle.skip=true \
     -Dspotless.check.skip=true \
     -Denforcer.skip=true \

pom.xml

@@ -2163,12 +2163,13 @@ under the License.
 				<plugin>
 					<groupId>org.apache.maven.plugins</groupId>
 					<artifactId>maven-javadoc-plugin</artifactId>
-					<version>2.9.1</version><!--$NO-MVN-MAN-VER$-->
+					<version>3.8.0</version>
 					<configuration>
 						<quiet>true</quiet>
 						<detectOfflineLinks>false</detectOfflineLinks>
-						<additionalJOptions combine.children="append">
+						<additionalJOptions>
 							<additionalJOption>-Xdoclint:none</additionalJOption>
+							<additionalJOption>--allow-script-in-comments</additionalJOption>
 						</additionalJOptions>
 					</configuration>
 				</plugin>