TargetSize doesn't work

[paipeng]

by using the following code,

ImageWriter writer = ImageIO.getImageWritersByMIMEType("image/webp").next();

// Configure encoding parameters
WebPWriteParam writeParam = new WebPWriteParam(writer.getLocale());
writeParam.setCompressionMode(ImageWriteParam.MODE_EXPLICIT);
writeParam.setCompressionType(writeParam.getCompressionTypes()[WebPWriteParam.LOSSY_COMPRESSION]);
writeParam.setTargetSize(40000);

The output webp file doesn't be changed, by adjusting setTargetSize values.