This buildfile is part of projectlombok.org. It sets up the build itself. Full eclipse testing requires downloading a native SWT binding. This script knows how to download for OS = [mac, linux, or windows] and architecture = [aarch64 or x86-64]. You have something different, you unique snowflake you. Your OS: "${os.name}", Your arch: "${os.arch}". 0 build ver has been incremented, neccessitating a clean... ${build.version} A new version of ivyplusplus was required and has been downloaded. Rerun the script to continue. To ensure stable builds and avoid accessing API that was not available in JDK6, most of lombok is set up to build against OpenJDK6's runtime, which will now be downloaded... To test java8, we need a java8 runtime, which will now be downloaded... To test in eclipse, we need a java runtime, which will now be downloaded... Supply ant with -Ddeps.conf=confname to pick the configuration you want to fetch ant needs to be at least v1.10.0 or higher to build lombok. Your version is: ${ant.version} lombok must be compiled on jdk11 or later. Your version is: ${ant.java.version}