// The default statement: just return the old value.
// This case should not be reached.
SwitchCase defaultCase = ast.newSwitchCase();
defaultCase.setExpression(null);
switchStatement.statements().add(defaultCase);
ReturnStatement defaultReturn = ast.newReturnStatement();
defaultReturn.setExpression((Expression) ASTNode.copySubtree(ast,
assignment.getLeftHandSide()));
switchStatement.statements().add(defaultReturn);