boolean (@NotNull PsiExpression operand) { if (operand instanceof PsiLiteralExpression) { return true; } else if (operand instanceof PsiPolyadicExpression polyadic) { for (PsiExpression expression : polyadic.getOperands()) { if (!isOnlyLiterals(expression)) return false; } return true; } else if (operand instanceof PsiParenthesizedExpression) { final PsiExpression expression = PsiUtil.skipParenthesizedExprDown(operand); if (expression != null && !isOnlyLiterals(expression)) return false; return true; } else { return false; } }