code: public Collection<Object> getAll(String name) {
      Object value = get(name);
      if (value == null) {
        return Collections.emptySet();
      }
      if (value instanceof Collection<?>) {
        @SuppressWarnings("unchecked")
        Collection<Object> collectionValue = (Collection<Object>) value;
        return Collections.unmodifiableCollection(collectionValue);
      }
      return Collections.singleton(value);
    }
docs: Returns all query parameter values for the given query parameter name.
  
  @param name query parameter name
  @return unmodifiable collection of query parameter values (possibly empty)