[JDK 11] mvn package -Pdocs fails

[ERROR] Failed to execute goal org.apache.maven.plugins:maven-javadoc-plugin:3.0.1:javadoc (default) on project hadoop-common: 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] /Users/aajisaka/git/hadoop/hadoop-common-project/hadoop-common/target/generated-sources/java/org/apache/hadoop/ipc/protobuf/RpcHeaderProtos.java:3467: error: cannot find symbol
[ERROR]       com.google.protobuf.GeneratedMessageV3 implements
[ERROR]                          ^
(snip)