I don't think you can disable auto-boxing outright while maintaining the target compile version - that's a feature of the specific Java version.
What you can do in IntelliJ is change the inspection level of Auto-boxing to "Error". To do that:
- Go to Settings > Inspections, and type "boxing" into the search bar.
- Click on "Auto-boxing".
- Set the severity to "Error". This will cause the inspections test to report any occurrence of auto-boxing as an error. You should do the same for auto-unboxing as well.
Further down the line, you can add code inspections which run when testing the code (PMD, FindBugs, Cobertura, et. al.) which will fail the build if anything is being auto-boxed or auto-unboxed.