private static List<String> splitAttribute(final String value) {
        final ArrayList<String> list = new ArrayList<>();

        if (value != null) {
            final StringTokenizer tokenizer = new StringTokenizer(value);
            while (tokenizer.hasMoreTokens()) {
                list.add(tokenizer.nextToken());
            }
        }

        return list;
    }
It must be called initially at once before all other getResource*() methods are called.

public to be called from org.embulk.cli. Not for plugins. Not guaranteed.
embulk-core/src/main/java/org/embulk/cli/SelfContainedJarFiles.java