[ERROR] Failed to execute goal org.apache.maven.plugins:maven-javadoc-plugin:3.0.1:javadoc-no-fork (default-cli) on project hadoop-hdfs-rbf: An error has occurred in Javadoc report generation:
[ERROR] Exit code: 1 - javadoc: warning - You have specified the HTML version as HTML 4.01 by using the -html4 option.
[ERROR] The default is currently HTML5 and the support for HTML 4.01 will be removed
[ERROR] in a future release. To suppress this warning, please ensure that any HTML constructs
[ERROR] in your comments are valid in HTML5, and remove the -html4 option.
[ERROR] javadoc: error - The code being documented uses modules but the packages defined in https://docs.oracle.com/javase/8/docs/api/ are in the unnamed module.