This has been observed once on Windows X64.
Please refer to the following test output. I suppose this is a test bug. The test looks to be trying to access files under workspace rather than the test work dir:
 java.security.AccessControlException: access denied ("java.io.FilePermission" "C:\jenkins\workspace\9-dev\jaxp\test\javax\xml\jaxp\unittest\validation\Bug6773084In\Bug6773084_11.xml" "read")


----------System.out:(60/1343)----------
[TestNG] Running:
  javax/xml/jaxp/unittest/validation/Bug6773084Test.java

Waiting for barrier: 0
test validation.Bug6773084Test.test(): success
Waiting for barrier: 24
Waiting for barrier: 23
Waiting for barrier: 22
Waiting for barrier: 21
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Waiting for barrier: 19
Waiting for barrier: 18
Waiting for barrier: 17
Waiting for barrier: 16
Waiting for barrier: 15
Waiting for barrier: 14
Waiting for barrier: 13
Waiting for barrier: 12
Waiting for barrier: 11
Waiting for barrier: 10
Waiting for barrier: 9
Waiting for barrier: 8
Waiting for barrier: 7
Waiting for barrier: 6
Waiting for barrier: 5
Waiting for barrier: 4
Waiting for barrier: 3
Waiting for barrier: 2
Waiting for barrier: 1
Validating....
Validating....
Validating....
Validating....
Validating....
Validating....
Validating....
Validating....
Validating....
Validating....
Validating....
Validating....
Validating....
Validating....
Validating....
Validating....
Validating....
Validating....
Validating....
Validating....
Validating....
Validating....
Validating....
Validating....
Validating....

===============================================
javax/xml/jaxp/unittest/validation/Bug6773084Test.java
Total tests run: 1, Failures: 0, Skips: 0
===============================================

----------System.err:(13/1343)*----------
java.security.AccessControlException: access denied ("java.io.FilePermission" "C:\\jenkins\\workspace\\9-dev\\jaxp\\test\\javax\\xml\\jaxp\\unittest\\validation\\Bug6773084In\\Bug6773084_11.xml" "read")
at java.security.AccessControlContext.checkPermission(java.base@9-ea/AccessControlContext.java:468)
at java.security.AccessController.checkPermission(java.base@9-ea/AccessController.java:894)
at java.lang.SecurityManager.checkPermission(java.base@9-ea/SecurityManager.java:548)
at java.lang.SecurityManager.checkRead(java.base@9-ea/SecurityManager.java:887)
at java.io.File.isDirectory(java.base@9-ea/File.java:845)
at java.io.File.toURI(java.base@9-ea/File.java:733)
at javax.xml.parsers.DocumentBuilder.parse(java.xml@9-ea/DocumentBuilder.java:205)
at validation.Bug6773084Test$XMLValiddator.run(Bug6773084Test.java:124)
at java.util.concurrent.ThreadPoolExecutor.runWorker(java.base@9-ea/ThreadPoolExecutor.java:1158)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(java.base@9-ea/ThreadPoolExecutor.java:632)
at java.lang.Thread.run(java.base@9-ea/Thread.java:843)
STATUS:Failed.`main' threw exception: java.security.AccessControlException: access denied ("java.io.FilePermission" "C:\\jenkins\\workspace\\9-dev\\jaxp\\test\\javax\\xml\\jaxp\\unittest\\validation\\Bug6773084In\\Bug6773084_11.xml" "read")