@Test
public void testCreatePostRequest() throws IOException, ServletException, URISyntaxException, NullPointerException {
    URI newTargetUri = new URI(targetUriPost);
    cdsRequestBuilder = new CDSRequestBuilder();
    HttpPost httpPost = cdsRequestBuilder.createPostRequest(mockClientRequest, newTargetUri);
    // Parse the entity
    String httpPostBody = IOUtils.toString(httpPost.getEntity().getContent());
    // Perform evaluation
    Assert.assertNotNull(httpPost);
    Assert.assertEquals(httpPost.getHeaders(HttpHeaders.HOST)[0].toString(), ("Host: " + newTargetUri.getHost()));
    Assert.assertTrue(httpPost.getHeaders(HttpHeaders.CONTENT_LENGTH).length == 0);
    Assert.assertTrue(httpPostBody.contains("payload"));
    Assert.assertTrue(httpPostBody.contains("file"));
    Assert.assertTrue(httpPostBody.contains(testFileBinaryData));
}

private HttpEntity convertInputStreamToMultiPart(Collection<Part> clientParts, String boundary) throws IOException {
    Part payload = null;
    Part file = null;
    for (Part part : clientParts) {
        if (part.getName().equalsIgnoreCase("payload")) {
            payload = part;
        } else if (part.getName().equalsIgnoreCase("file")) {
            file = part;
    if(payload == null) {
        logIt.error("Failed to extract payload - no payload found");
        throw new IllegalStateException("Payload is missing from client request.");
    if(file == null || file.getSubmittedFileName().length() == 0) {
        logIt.error("Failed to extract file - no file found");
        throw new IllegalStateException("File is missing from client request.");
    logIt.info("Payload is parsed from client: {}", IOUtils.toString(payload.getInputStream()));
    return MultipartEntityBuilder.create()
            .addTextBody("payload", IOUtils.toString(payload.getInputStream()))
            .addBinaryBody("file", file.getInputStream(), ContentType.parse("application/pdf"), file.getSubmittedFileName())
            .setContentType(ContentType.parse(MediaType.APPLICATION_FORM_URLENCODED))
            .setBoundary(boundary)
            .build();
}

when(mockFilePart.getName()).thenReturn("file");
    when(mockFilePart.getSubmittedFileName()).thenReturn(testFileName);
    when(mockFilePart.getInputStream()).thenReturn(IOUtils.toInputStream(testFileBinaryData));

org.apache.http.ContentTooLongException: Content length is unknown