Exception when reading findbugs result file ():

java.io.FileNotFoundException: c:\hudson\workspace\job\src\main\com\test(Access is denied)
at java.io.FileInputStream.open(Native Method)
at java.io.FileInputStream.<init>(Unknown Source)
at java.io.FileReader.<init>(Unknown Source)
at hudson.plugins.violations.generate.OutputFileModel.open(OutputFileModel.java:152)
at hudson.plugins.violations.generate.OutputFileModel.outputContents(OutputFileModel.java:164)
at hudson.plugins.violations.generate.OutputFileModel.execute(OutputFileModel.java:84)
at hudson.plugins.violations.generate.ExecuteFilePath.execute(ExecuteFilePath.java:45)
at hudson.plugins.violations.generate.GenerateXML.execute(GenerateXML.java:47)
at hudson.plugins.violations.ViolationsCollector.invoke(ViolationsCollector.java:124)
at hudson.plugins.violations.ViolationsCollector.invoke(ViolationsCollector.java:27)

Causes the build to fail because it tries to read a folder.

The following findbugs.xml output generates the exception:
<SourceLine classname="com.test.JiBX_general_bindingFactory" sourcefile="" sourcepath="com/test/"/>

This is because of the sourcepath set by JiBX in the generated classes which matches a directory and not a file.
However Violation plugin should not exception.

Fix is easy, change file.exists() into file.isFile() in AbsoluteFileFinder.java (patch attached).
As Violation will fail when a directory is provided, it also needs to protect against it.