MultipartFormEntity buildEntity()

in httpclient5/src/main/java/org/apache/hc/client5/http/entity/mime/MultipartEntityBuilder.java [203:264]
60 lines of code
18 McCabe index (conditional complexity)

    MultipartFormEntity buildEntity() {
        String boundaryCopy = boundary;
        if (boundaryCopy == null && contentType != null) {
            boundaryCopy = contentType.getParameter("boundary");
        }
        if (boundaryCopy == null) {
            boundaryCopy = generateBoundary();
        }
        Charset charsetCopy = charset;
        if (charsetCopy == null && contentType != null) {
            charsetCopy = contentType.getCharset();
        }
        final List<NameValuePair> paramsList = new ArrayList<>(2);
        paramsList.add(new BasicNameValuePair("boundary", boundaryCopy));
        if (charsetCopy != null) {
            paramsList.add(new BasicNameValuePair("charset", charsetCopy.name()));
        }
        final NameValuePair[] params = paramsList.toArray(EMPTY_NAME_VALUE_ARRAY);

        final ContentType contentTypeCopy;
        if (contentType != null) {
            contentTypeCopy = contentType.withParameters(params);
        } else {
            boolean formData = false;
            if (multipartParts != null) {
                for (final MultipartPart multipartPart : multipartParts) {
                    if (multipartPart instanceof FormBodyPart) {
                        formData = true;
                        break;
                    }
                }
            }

            if (formData) {
                contentTypeCopy = ContentType.MULTIPART_FORM_DATA.withParameters(params);
            } else {
                contentTypeCopy = ContentType.create("multipart/mixed", params);
            }
        }
        final List<MultipartPart> multipartPartsCopy = multipartParts != null ? new ArrayList<>(multipartParts) :
                Collections.emptyList();
        final HttpMultipartMode modeCopy = mode != null ? mode : HttpMultipartMode.STRICT;
        final AbstractMultipartFormat form;
        switch (modeCopy) {
            case LEGACY:
                form = new LegacyMultipart(charsetCopy, boundaryCopy, multipartPartsCopy);
                break;
            case EXTENDED:
                if (contentTypeCopy.isSameMimeType(ContentType.MULTIPART_FORM_DATA)) {
                    if (charsetCopy == null) {
                        charsetCopy = StandardCharsets.UTF_8;
                    }
                    form = new HttpRFC7578Multipart(charsetCopy, boundaryCopy, multipartPartsCopy);
                } else {
                    form = new HttpRFC6532Multipart(charsetCopy, boundaryCopy, multipartPartsCopy);
                }
                break;
            default:
                form = new HttpStrictMultipart(StandardCharsets.US_ASCII, boundaryCopy, multipartPartsCopy);
        }
        return new MultipartFormEntity(form, contentTypeCopy, form.getTotalLength());
    }