When you drop an old JAR which needs to be fixed into ./deps folder and have code that refers to it already (like a new plugin), the module-fixer fails to transform the JAR into a module, as the compiler plugin(?) holds an handle to the JAR.

Workaround:

• drop the JAR into deps
• ./build (fixes the JAR) // without this call, the next build will fail
• insert new plugin code requiring the new module
• ./build