Build failed: where's my bc4j.xcfg?

Yesterday and this morning I lost a lot of time with building failures, trying to build our ADF HumanTask forms. We used a adf-lib for amongst others XML DataControls, and reusable page-comoponents.

Trying to build the ear file, and actually that adf-lib, I got an error stating 'Unable to copy to output directory ... <default-package>/common/bc4j.xcfg not found'. Indeed in that default ADFBc folder the bc4j.xcfg is not available, nor anywhere in our whole project or workspace.

After a while of searching on our friend Google, I found this post of Andrejus Baranovski.

Apparently in Jdeveloper 11gR2 Oracle introduced a caching mechanism for the IDE.Probably some paging mechanism where Jdeveloper pages files in memory to disk. It's, to be honest, actually one of the behaviours I did not like in Eclipse. I liked the 'what you see is what you edit' approach of JDeveloper.

And since I'm mostly a SOA and BPM developer, I was stuck in JDeveloper 11gR1, never go to R2. But now in 12c I ran into this behaviour of JDeveloper. Anyway, JDeveloper does this caching on Application level, thus on a per Application basis. So go to Application Properties:

 Then to the node IDE Performance Cache:

 

There you'll find the default location of your cache. In that folder you'll find a .data subfolder, containing caching data of all or some of your Application projects. Close JDeveloper (since under Windows it locks those files) and clear that folder.

Since this folder is a subfolder of the application, by default, you should make sure to ignore it with versioning, override the folder with a path outside of your subversion working copy.