code: public static String getEsBuildVersion() {
          URL url = ApimanEmbeddedElastic.class.getResource("apiman-embedded-elastic.properties");
          if (url == null) {
              throw new RuntimeException("embedded-elastic.properties missing.");
          } else {
              Properties allProperties = new Properties();
              try(InputStream is = url.openStream()){
                  allProperties.load(is);
                  return Optional
                          .ofNullable(allProperties.getProperty("apiman.embedded-es-version"))
                          .orElseThrow(() -> new RuntimeException("apiman.embedded-es-version"));
              } catch (IOException e) {
                  throw new RuntimeException(e);
              }
          }
      }
docs: testing.