}
    }

    private FileTree asFileTree(File jdkArchive) {
        final String extension = FilenameUtils.getExtension(jdkArchive.getName());
        if (Objects.equals(extension, "zip")) {
            return operations.zipTree(jdkArchive);
        }
        return operations.tarTree(operations.getResources().gzip(jdkArchive));
    }

        @Override
        public boolean equals(Object obj) {
            ArtifactKey other = (ArtifactKey) obj;
            return file.equals(other.file) && Objects.equals(classifier, other.classifier) && Objects.equals(extension, other.extension);
        }

        @Override
        public int hashCode() {
            return file.hashCode() ^ Objects.hash(classifier, extension);
        }
    }

    /**