Difficulty Generating Doc

[SubutaDan]

My application is failing on startup if I try to generate doc. I tried the demo application and it seems to be doing the same thing:

Exception in thread "main" java.io.IOException: No such file or directory
	at java.base/java.io.UnixFileSystem.createFileExclusively(Native Method)
	at java.base/java.io.File.createNewFile(File.java:1035)
	at io.github.manusant.ss.SwaggerHammer.extractUiFolder(SwaggerHammer.java:78)
	at io.github.manusant.ss.SwaggerHammer.extractUi(SwaggerHammer.java:58)
	at io.github.manusant.ss.SwaggerHammer.prepareUi(SwaggerHammer.java:40)
	at io.github.manusant.ss.SparkSwagger.generateDoc(SparkSwagger.java:127)
	at io.github.manusant.ss.demo.ThorApi.main(ThorApi.java:27)

In both cases if I remove:

.generateDoc()

then the program start successfully.

I'm thinking I have broken something in my environment or am making some other kind of basic mistake but I haven't been able to spot it. Any thoughts? Thanks.