new_field.default = field.default  # type: ignore[misc]
    new_field.required = field.required  # type: ignore[misc]
    new_field.model_config = field.model_config  # type: ignore[attr-defined]
    new_field.field_info = field.field_info
    new_field.allow_none = field.allow_none  # type: ignore[attr-defined]
    new_field.validate_always = field.validate_always  # type: ignore[attr-defined]

      <name>Metadata</name>
      <version>1.0.0+</version>
      <fields>
        <field xml.attribute="true" xml.tagName="modelVersion">
          <name>modelVersion</name>
          <version>1.1.0+</version>
          <type>String</type>
          <description>The version of the underlying metadata model.</description>
        </field>
        <field>
          <name>groupId</name>
          <version>1.0.0+</version>

        final FessConfig fessConfig = ComponentUtil.getFessConfig();
        return searchEngineClient.getDocument(fessConfig.getIndexDocumentUpdateIndex(), builder -> {
            builder.setQuery(QueryBuilders.idsQuery().addIds(id));
            builder.setFetchSource(fields, null);
            return true;
        }).orElse(null);
    }

                response_field = create_response_field(name=response_name, type_=model)
                response_fields[additional_status_code] = response_field
        if response_fields:
            self.response_fields: Dict[Union[int, str], ModelField] = response_fields
        else:
            self.response_fields = {}

        assert callable(endpoint), "An endpoint must be a callable"

        final StringBuilder buf = new StringBuilder(100);
        buf.append(form.q);
        if (!form.fields.isEmpty() && form.fields.containsKey(LABEL_FIELD)) {
            final String[] values = form.fields.get(LABEL_FIELD);
            final List<String> labelList = new ArrayList<>();
            if (values != null) {
                Collections.addAll(labelList, values);

                    if (source != null) {
                        docMap.putAll(source);
                    }
                    final Map<String, DocumentField> fields = hit.getFields();
                    if (fields != null) {
                        docMap.putAll(fields.entrySet().stream()
                                .collect(Collectors.toMap(Entry::getKey, e -> (Object) e.getValue().getValues())));
                    }

    ```

For example, in one of the ways the OAuth2 specification can be used (called "password flow") it is required to send a `username` and `password` as form fields.

The <abbr title="specification">spec</abbr> requires the fields to be exactly named `username` and `password`, and to be sent as form fields, not JSON.

        String[] fields = (String[]) propMap.get(LOGGING_SEARCH_DOCS_FIELDS);
        if (fields == null) {
            fields = split(getLoggingSearchDocsFields(), ",").get(stream -> stream.map(String::trim).toArray(n -> new String[n]));
            propMap.put(LOGGING_SEARCH_DOCS_FIELDS, fields);
        }
        return fields;
    }

    String getSchedulerTargetName();

    String INDEX_ADMIN_LONG_FIELDS = "index.admin.long.fields";

    /** The key of the configuration. e.g. boost */
    String INDEX_ADMIN_FLOAT_FIELDS = "index.admin.float.fields";

    /** The key of the configuration. e.g.  */
    String INDEX_ADMIN_DOUBLE_FIELDS = "index.admin.double.fields";

    /** The key of the configuration. e.g. url,title,role,boost */
    String INDEX_ADMIN_REQUIRED_FIELDS = "index.admin.required.fields";

            fields will be ignored at serialization time.
            """
        ),
    ] = None,
    convert_underscores: Annotated[
        bool,
        Doc(
            """
            Automatically convert underscores to hyphens in the parameter field name.

            Read more about it in the