SimplifyMethodHandler的buildFieldDetails方法优化

[YanX408]

private Map<String, List<SimplifyDocField>> buildFieldDetails(final List<SimplifyDocField> fields) {
    if (CollectionUtil.isEmpty(fields)) {
        return null;
    }
    final Map<String, List<SimplifyDocField>> map = new LinkedHashMap<>();
    for (SimplifyDocField docField : fields) {
        traversal(docField, map);
    }
    return map;
}
private void traversal(SimplifyDocField field, Map<String, List<SimplifyDocField>> map) {
    if (field.getEntries() == null) {
        return;
    }
    List<SimplifyDocField> entries = field.getEntries();
    map.put(field.getName(), entries);
    for (SimplifyDocField entry : entries) {
        traversal(entry, map);
    }
}