code: private Map findLoaders() {
          Map loaders = getContainer().getComponentDescriptorMap(ProviderLoader.class.getName());
          if (loaders == null) {
              throw new Error("No provider loaders found");
          }
  
          Set keys = loaders.keySet();
          Map found = null;
          ProviderLoader defaultLoader = null;
  
          for (Iterator iter = keys.iterator(); iter.hasNext();) {
              String key = (String)iter.next();
  
              ProviderLoader loader;
  
              try {
                  loader = (ProviderLoader) getContainer().lookup(ProviderLoader.class.getName(), key);
              }
              catch (Exception e) {
                  log.warn("Failed to lookup provider loader for key: {}", key, e);
                  continue;
              }
  
              if (loader != null) {
                  if (found == null) {
                      // we need an ordered map
                      found = new LinkedHashMap();
                  }
                  if (key.equals(SELECT_DEFAULT)) {
                      defaultLoader = loader;
                  }
                  else {
                      found.put(key, loader);
                  }
              }
          }
  
          // the default should be added at the end (as fallback)
          assert defaultLoader != null;
          found.put(SELECT_DEFAULT, defaultLoader);
  
          return found;
      }
docs: Find any provider loaders which are available in the container.