code: private Map<ConfigurationKey, Object> getObsoleteSystemProperties() {
          Map<ConfigurationKey, Object> found = new EnumMap<ConfigurationKey, Object>(ConfigurationKey.class);
          String concurrentDeployment = getSystemProperty("org.jboss.weld.bootstrap.properties.concurrentDeployment");
          if (concurrentDeployment != null) {
              processKeyValue(found, ConfigurationKey.CONCURRENT_DEPLOYMENT, concurrentDeployment);
              found.put(ConfigurationKey.CONCURRENT_DEPLOYMENT, ConfigurationKey.CONCURRENT_DEPLOYMENT.convertValue(concurrentDeployment));
          }
          String preloaderThreadPoolSize = getSystemProperty("org.jboss.weld.bootstrap.properties.preloaderThreadPoolSize");
          if (preloaderThreadPoolSize != null) {
              found.put(ConfigurationKey.PRELOADER_THREAD_POOL_SIZE, ConfigurationKey.PRELOADER_THREAD_POOL_SIZE.convertValue(preloaderThreadPoolSize));
          }
          return found;
      }
docs: Try to get a system property for obsolete keys. The value is automatically converted - a runtime exception may be thrown during conversion.
  
  @return all the properties whose system property keys were different in previous versions