How to set unique id to document where creating a document from plugin

Hi All,

I am creating a document in custom plugin, while I am generating id for that document I'm getting following error.

Code : long id = cs.create(document, ContentConstants.UNIQUE_FOR_PARENT);
document.setId(id);

Error: com.appiancorp.suiteapi.content.exceptions.InsufficientNameUniquenessException: Name is insufficiently unique

Can some one please help me.

Thanks 

Pradeep