The Maven Central Repository hosts over 11 million packages. As Maven itself is a build tool for Java, the majority of these packages are Java archives.
This research aims to analyze these packages and look into various build aspects of these projects (the research questions): are Java modules used, what Java versions are used and how is the compiler configured? This is done by downloading a subset of these packages and looking at both the final artifact and the attached Project Object Model (Maven configuration). Specifically, one version is randomly selected from each distinct package hosted on Maven Central and then analyzed.
This research helps inform Java language developers and library maintainers. It captures parts of the build system evolution over a span of more than a decade. Precisely, version adoption, reproducibility and desirable build features are all important metrics for project maintainers in any software ecosystem. In the end, 473352 packages were analyzed. Firstly, it was found that Java modules are rare: only 6919 (1.69% of the artifacts with an archive) of the packages use Java modules. Secondly, the most common Java version used is Java SE 8 (182476 packages) representing almost half of all analyzed packages. All long-term support versions (Java SE 8, 11, 17 and 21) make up roughly half of the available packages. Thirdly, only 54.98% of artifacts configure the Maven compiler plugin with the most used parameters being the source and target Java versions. The most common additional compiler flags are verbosity settings, providing more feedback and code analysis from both the linter and compiler.