code: protected void markStatementsForUpdate(StatementDocument currentDocument,
  			List<Statement> addStatements, List<Statement> deleteStatements) {
  		markStatementsForDeletion(currentDocument, deleteStatements);
  		markStatementsForInsertion(currentDocument, addStatements);
  	}
docs: Marks the given lists of statements for being added to or deleted from
  the given document, respectively. The current content of the document is
  compared with the requested changes to avoid duplicates (merging
  references of duplicate statements), and to avoid deletions of statements
  that have changed or ceased to exist.
  
  @param currentDocument
  the document with the current statements
  @param addStatements
  the list of new statements to be added
  @param deleteStatements
  the list of statements to be deleted