[CI] Secure Hdfs Fixture in JDK16

[albertzaharovits]

Build scan: https://gradle-enterprise.elastic.co/s/plztmz7djijsu

Repro line: ./gradlew ':x-pack:plugin:searchable-snapshots:qa:hdfs:integTestSecure' --tests "org.elasticsearch.xpack.searchablesnapshots.hdfs.HdfsSearchableSnapshotsIT" -Dtests.security.manager=true -Druntime.java=16

Reproduces locally?: Yes

Applicable branches: 7.x, master

Failure history:
https://build-stats.elastic.co/app/kibana#/discover?_g=(refreshInterval:(pause:!t,value:0),time:(from:now-90d,mode:quick,to:now))&_a=(columns:!(build.job-name,build.branch),index:b646ed00-7efc-11e8-bf69-63c8ef516157,interval:auto,query:(language:lucene,query:HdfsSearchableSnapshotsIT),sort:!(process.time-start,desc))
Failure excerpt:

  [run]	
    "/var/lib/jenkins/.java/openjdk16/bin/java" "$@" > run.log 2>&1 ; if [ $? != 0 ]; then touch run.failed; fi	
secureHdfsFixture output:	
-----------------------------------------	
  failure marker exists: true	
  pid file exists: false	
  ports file exists: false	
	
  [log]	
    Picked up JAVA_TOOL_OPTIONS: -Dfile.encoding=UTF8	
    Exception in thread "main" java.lang.IllegalArgumentException: Can't get Kerberos realm	
    	at org.apache.hadoop.security.HadoopKerberosName.setConfiguration(HadoopKerberosName.java:65)	
    	at org.apache.hadoop.security.UserGroupInformation.initialize(UserGroupInformation.java:296)	
    	at org.apache.hadoop.security.UserGroupInformation.setConfiguration(UserGroupInformation.java:342)	
    	at hdfs.MiniHDFS.main(MiniHDFS.java:99)	
    Caused by: java.lang.IllegalAccessException: class org.apache.hadoop.security.authentication.util.KerberosUtil cannot access class sun.security.krb5.Config (in module java.security.jgss) because module java.security.jgss does not export sun.security.krb5 to unnamed module @123a3fe3	
    	at java.base/jdk.internal.reflect.Reflection.newIllegalAccessException(Reflection.java:385)	
    	at java.base/java.lang.reflect.AccessibleObject.checkAccess(AccessibleObject.java:687)	
    	at java.base/java.lang.reflect.Method.invoke(Method.java:559)	
    	at org.apache.hadoop.security.authentication.util.KerberosUtil.getDefaultRealm(KerberosUtil.java:107)	
    	at org.apache.hadoop.security.HadoopKerberosName.setConfiguration(HadoopKerberosName.java:63)

[elasticmachine]

Pinging @elastic/es-security (Team:Security)

[albertzaharovits]

@jbaiera Do you have any hunches about this?

[jbaiera]

Seems related to #66972. I put in a fix for this for JDK 16 builds a little while back (#67391) but it seems that the issue has resurfaced. Looking at the command line for the secured hdfs fixture, it lacks the open exports argument that the fix PR was supposed to add. I suspect some small detail is keeping that from being added in the build. I'll investigate.

[elasticmachine]

Pinging @elastic/es-core-features (Team:Core/Features)

[cbuescher]

Some more today: https://gradle-enterprise.elastic.co/s/mvhntb4vvwnbc