in src/main/java/org/apache/maven/plugin/compiler/CompilerMojo.java [327:349]
private List<File> getCompileClasspathElements(MavenProject project) {
// 3 is outputFolder + 2 preserved for multirelease
List<File> list = new ArrayList<>(project.getArtifacts().size() + 3);
if (multiReleaseOutput) {
File versionsFolder = new File(project.getBuild().getOutputDirectory(), "META-INF/versions");
// in reverse order
for (int version = Integer.parseInt(getRelease()) - 1; version >= 9; version--) {
File versionSubFolder = new File(versionsFolder, String.valueOf(version));
if (versionSubFolder.exists()) {
list.add(versionSubFolder);
}
}
}
list.add(new File(project.getBuild().getOutputDirectory()));
for (Artifact a : project.getArtifacts()) {
list.add(a.getFile());
}
return list;
}