@Override
  public PropertySource load() {
    Properties properties = System.getProperties();
    Map<String, Object> ratelimiterProperties = new HashMap<String, Object>();
    Set<String> names = properties.stringPropertyNames();
    for (String name : names) {
      if (name.startsWith(PropertyConstants.PROPERTY_KEY_PREFIX)) {
        ratelimiterProperties.put(name, properties.get(name));
      }
    }
    PropertySource source = new PropertySource();
    source.addProperties(ratelimiterProperties);
    return source;
  }
This class loads environment configuration from JVM environment variables.
src/main/java/com/eudemon/ratelimiter/env/loader/JvmPropertySourceLoader.java