@Override
    public Map<Object, Struct> asMap() {
      return value.entrySet().stream()
        .map(e -> Map.entry(e.getKey(), e.getValue()))
        .collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue));
    }
Returns a new list where each element of this list has been expanded to the list of elements returned by
{@code mapper}.
<p>
Individual items are treated as a list containing just that item.
planetiler-core/src/main/java/com/onthegomap/planetiler/reader/Struct.java