images are not displayed for upload attachments with storeContent API in Repository

Hi Team,
We are uploading the attachments to the process template by using below code. But we are not able to see the .gif images of the attachments using the storeContent API.

 String att[] = attachment.split("\r\n");
        IProcessAttachmentHandle[] attachementhandle = new IProcessAttachmentHandle[att.length];
        IProcessItem[] attachments = new IProcessItem[att.length + 1];
        for (int i = 0; i < att.length; i++) {
          IProcessAttachment processAttachment = processItemService.createProcessAttachment();
          IContent attachmentContent =
              this.teamRepo.contentManager().storeContent(IContent.CONTENT_TYPE_UNKNOWN, att[i], monitor);
          processAttachment.setContent(attachmentContent);
          processAttachment.setPath(att[i]);
          processAttachment.setProcessContainer(workingCopy);
          IProcessAttachmentHandle handle =
              (IProcessAttachmentHandle) IProcessAttachment.ITEM_TYPE.createItemHandle(processAttachment.getItemId(),
                  null);
          System.out.println("UUID.valueOf(itemId):" + processAttachment.getItemId() + ":" + att[i]);
          attachementhandle[i] = handle;
          workingCopy.addAttachment(processAttachment);
          attachments[i] = processAttachment;