The new Java toolchain feature cannot be used at the project level in combination with source and/or target compatibility

settings that are lower than Java 9.

This means that if you want to use the new Java toolchain feature, you must set the source and/or target compatibility to Java 9 or higher for the entire project. If you have any modules or libraries that require a lower source or target compatibility, you will need to update them to be compatible with Java 9 or higher.

It is important to note that using the new Java toolchain feature may require changes to your build scripts and configurations, as well as potentially updating any dependencies or libraries that are not compatible with Java 9 or higher.

Overall, the new Java toolchain feature can provide benefits such as improved performance and security, so it may be worth considering upgrading your project to be compatible with Java 9 or higher in order to take advantage of this feature.