Re: Upgrade to 5.0.0 resulted in IOException message

On Wed, 3 Feb 2021, Bryan Coleman wrote:
> java.io.IOException: Your InputStream was neither an OLE2 stream, nor an 
> OOXML stream or you haven't provide the poi-ooxml*.jar in the 
> classpath/modulepath - FileMagic: OLE2, having providers: 
> [org.apache.poi.xssf.usermodel.XSSFWorkbookFactory@40086342]

That's very odd - you have the main POI jar there (need it for 
WorkbookFactory), but somehow have lost the reference to the HSSF classes 
which also live there...

> Note: It works when running in my IDE; however, when it runs from a 
> (mega) jar (built by ant), we get the exception above.

Ah, I suspect something is clobbering some files when it merges stuff into 
a mega jar. My guess is it's the /META-INF/services files, and your mega 
jar is taking just one rather than merging as it needs to

Can you post details of how you're building the mega jar, and/or look up 
how to get the tool/task you're using to merge not overwrite ServiceLoader 
/ Java Service Provider Interface services files?

Nick