@Override
    public String getExpressionString() {
        return expression.getExpressionString();
    }
@Test
    void testGetExpressionString() {
        ExpressionParser parser = new SpelExpressionParser();
        Expression defaultExpression = parser.parseExpression("'Hello World'.concat('!')");
        SpringELExpression springELExpression = new SpringELExpression(defaultExpression);
        Assertions.assertEquals(springELExpression.getExpressionString(), "'Hello World'.concat('!')");
    }