private Optional<Path> normalizePathInEmbulkPropertiesFile(
            final String propertyName,
            final Properties embulkPropertiesFromFile,
            final Path embulkHome) {
        final List<Path> paths = normalizePathsInEmbulkPropertiesFile(
                propertyName, embulkPropertiesFromFile, embulkHome, false);
        if (paths.size() > 1) {
            throw new IllegalStateException("Multiple paths returned for an unsplit path.");
        }

        if (paths.isEmpty()) {
            return Optional.empty();
        }
        return Optional.of(paths.get(0));
    }
Returns normalized paths in an environment variable.

<p>Note that a path in an environment variable should be an absolute path.
embulk-core/src/main/java/org/embulk/cli/EmbulkSystemPropertiesBuilder.java