if (ContentTypes.IMAGE_JPEG.equals(contentType))
ret = new ImageJpegPart(externalTarget);
else if (ContentTypes.IMAGE_PNG.equals(contentType))
ret = new ImagePngPart(externalTarget);
else if (ContentTypes.IMAGE_GIF.equals(contentType))
ret = new ImageGifPart(externalTarget);
else if (ContentTypes.IMAGE_TIFF.equals(contentType))
ret = new ImageTiffPart(externalTarget);
else if (ContentTypes.IMAGE_BMP.equals(contentType))
ret = new ImageBmpPart(externalTarget);
else if (ContentTypes.IMAGE_EMF.equals(contentType))