public static Properties getEsVersion() {
        if (esVersions == null) {
            InputStream is = EsConstants.class.getResourceAsStream("apiman-es.properties");
            Properties p = new Properties();
            try {
                p.load(is);
            } catch (IOException e) {
                throw new UncheckedIOException(e);
            }
            esVersions = p;
        }
        return esVersions;
    }
Reads the elasticsearch version from the maven-generated properties file

@return version the elasticsearch version
common/es/src/main/java/io/apiman/common/es/util/EsConstants.java