code: protected void markStatementsForInsertion(
  			StatementDocument currentDocument, List<Statement> addStatements) {
  		for (Statement statement : addStatements) {
  			addStatement(statement, true);
  		}
  
  		for (StatementGroup sg : currentDocument.getStatementGroups()) {
  			if (this.toKeep.containsKey(sg.getProperty())) {
  				for (Statement statement : sg) {
  					if (!this.toDelete.contains(statement.getStatementId())) {
  						addStatement(statement, false);
  					}
  				}
  			}
  		}
  	}
docs: Marks a given list of statements for insertion into the current document.
  Inserted statements can have an id if they should update an existing
  statement, or use an empty string as id if they should be added. The
  method removes duplicates and avoids unnecessary modifications by
  checking the current content of the given document before marking
  statements for being written.
  
  @param currentDocument
  the document with the current statements
  @param addStatements
  the list of new statements to be added