Fail to analyze java files with extension .jav

Caused by: org.sonar.squid.api.AnalysisException: Sonar is unable to analyze file : 'xxx/Foo.jav'
	at org.sonar.java.ast.AstScanner.scan(AstScanner.java:132)
	at org.sonar.java.JavaSquid.scanSources(JavaSquid.java:113)
	at org.sonar.java.JavaSquid.scan(JavaSquid.java:107)
	at org.sonar.plugins.java.JavaSquidSensor.analyse(JavaSquidSensor.java:79)
	at org.sonar.batch.phases.SensorsExecutor.execute(SensorsExecutor.java:72)
	at org.sonar.batch.phases.PhaseExecutor.execute(PhaseExecutor.java:114)
	at org.sonar.batch.scan.ModuleScanContainer.doAfterStart(ModuleScanContainer.java:142)
	at org.sonar.api.platform.ComponentContainer.startComponents(ComponentContainer.java:88)
	at org.sonar.api.platform.ComponentContainer.execute(ComponentContainer.java:73)
	at org.sonar.batch.scan.ProjectScanContainer.scan(ProjectScanContainer.java:186)
	at org.sonar.batch.scan.ProjectScanContainer.scanRecursively(ProjectScanContainer.java:181)
	at org.sonar.batch.scan.ProjectScanContainer.scanRecursively(ProjectScanContainer.java:179)
	at org.sonar.batch.scan.ProjectScanContainer.doAfterStart(ProjectScanContainer.java:174)
	at org.sonar.api.platform.ComponentContainer.startComponents(ComponentContainer.java:88)
	at org.sonar.api.platform.ComponentContainer.execute(ComponentContainer.java:73)
	at org.sonar.batch.scan.ScanTask.scan(ScanTask.java:57)
	at org.sonar.batch.scan.ScanTask.execute(ScanTask.java:45)
	at org.sonar.batch.bootstrap.TaskContainer.doAfterStart(TaskContainer.java:82)
	at org.sonar.api.platform.ComponentContainer.startComponents(ComponentContainer.java:88)
	at org.sonar.api.platform.ComponentContainer.execute(ComponentContainer.java:73)
	at org.sonar.batch.bootstrap.BootstrapContainer.executeTask(BootstrapContainer.java:156)
	at org.sonar.batch.bootstrap.BootstrapContainer.doAfterStart(BootstrapContainer.java:144)
	at org.sonar.api.platform.ComponentContainer.startComponents(ComponentContainer.java:88)
	at org.sonar.api.platform.ComponentContainer.execute(ComponentContainer.java:73)
	at org.sonar.batch.bootstrapper.Batch.startBatch(Batch.java:92)
	at org.sonar.batch.bootstrapper.Batch.execute(Batch.java:74)
	at org.sonar.runner.batch.IsolatedLauncher.execute(IsolatedLauncher.java:45)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:606)
	at org.sonar.runner.impl.BatchLauncher$1.delegateExecution(BatchLauncher.java:87)
	... 31 more
Caused by: java.lang.NullPointerException
	at org.sonar.java.ast.visitors.SyntaxHighlighterVisitor.visitFile(SyntaxHighlighterVisitor.java:86)
	at com.sonar.sslr.impl.ast.AstWalker.walkAndVisit(AstWalker.java:67)
	at org.sonar.java.ast.AstScanner.scan(AstScanner.java:93)
	... 62 more
[ERROR]