gistfile1.txt

private FormDataMultiPart copyMultipart(FormDataMultiPart multiPart) {
        FormDataMultiPart copiedMultipart = new FormDataMultiPart();

        copiedMultipart.setMediaType(multiPart.getMediaType());
        copiedMultipart.setContentDisposition(multiPart.getContentDisposition());
        copiedMultipart.getHeaders().putAll(multiPart.getHeaders());

        for (BodyPart bodyPart : multiPart.getBodyParts()) {

            if (typeEquals(bodyPart.getMediaType(), APPLICATION_OCTET_STREAM_TYPE)) {
                FormDataBodyPart formDataBodyPart = (FormDataBodyPart) bodyPart;

/*                InputStream in = formDataBodyPart.getEntityAs(InputStream.class);
                ByteArrayOutputStream out = new ByteArrayOutputStream();
                Try.apply(() -> IOUtils.copy(in, out));

                InputStream btis = new ByteArrayInputStream(out.toByteArray());*/
                ContentDisposition cd = formDataBodyPart.getContentDisposition();

                OutputStream out = new ByteArrayOutputStream();
                TeeInputStream in = new TeeInputStream(formDataBodyPart.getEntityAs(InputStream.class), out);

                StreamDataBodyPart streamDataBodyPart = new StreamDataBodyPart(
                        formDataBodyPart.getName(),
                        in,
                        cd.getFileName(),
                        formDataBodyPart.getMediaType()
                );
                streamDataBodyPart.getHeaders().putAll(formDataBodyPart.getHeaders());

                copiedMultipart.bodyPart(streamDataBodyPart);
            } else {
                FormDataBodyPart fdbp = (FormDataBodyPart) bodyPart;

                FormDataBodyPart formDataBodyPart = new FormDataBodyPart(fdbp.getName(), fdbp.getEntity(), fdbp.getMediaType());

                copiedMultipart.bodyPart(formDataBodyPart);
            }

        }

        return copiedMultipart;
    }