I am trying to move/copy a folder from one location to another location it is giving me an error

Object reference not set to an instance of an object

but it is working fine with File.

I am using SOAP API copyIntoItems() function

copyService.copyIntoItems(sourceUrl, destinationUrl, fieldInformationCollection, fileContent, hld,result);

but in this API we compulsory need to pass file content(data blob) but I have an empty folder that I have to copy/move