docs: public static <C> Class<? extends C> findImplementation(Class<? super C> restrictionClass, String value) {
      // Add all from service files (i.e. jars)
      if(!contains(restrictionClass)) {
        ELKIServiceLoader.load(restrictionClass);
        ELKIServiceScanner.load(restrictionClass);
      }
      Entry e = data.get(restrictionClass);
      int pos = -1;
      Class<?> clazz = null;
      // First, try the lookup cache:
      if(e != null) {
        for(pos = 0; pos < e.len; pos++) {
          if(e.names[pos].equals(value)) {
            break;
          }
        }
        if(pos < e.len) {
          clazz = e.clazzes[pos];
        }
        else {
          pos = -1;
        }
      }
      else {
        if(LOG.isDebugging()) {
          LOG.debug("Requested implementations for unregistered type: " + restrictionClass.getName() + " " + value);
        }
      }
      // Next, try alternative versions:
      clazz = clazz != null ? clazz : tryAlternateNames(restrictionClass, value, e);
      if(clazz == null) {
        return null;
      }
  
      if(!restrictionClass.isAssignableFrom(clazz)) {
        LOG.warning("Invalid entry in service file for class " + restrictionClass.getName() + ": " + value);
        clazz = FAILED_LOAD;
      }
      if(e != null) {
        if(pos < 0) {
          e.addHit(value, clazz);
        }
        else {
          assert (e.names[pos].equalsIgnoreCase(value));
          e.clazzes[pos] = clazz;
        }
      }
      if(clazz == FAILED_LOAD) {
        return null;
      }
      @SuppressWarnings("unchecked")
      Class<? extends C> ret = (Class<? extends C>) clazz.asSubclass(restrictionClass);
      return ret;
    }