Spring SPEL: ternary operator always returns "false value" if used in property

Affects: Spring Framework\5.2.5, Spring Boot\2.2.6

If the SPEL ternary operator is used in @Value, application.properties or application.yml its not evaluated correctly. Not matter what the expression result is it always returns the "false value".

The following application

@SpringBootApplication
@ConfigurationProperties(prefix = "application")
class SpelTernaryApplication {
    var spel = ""
    var spel2 = ""

    @Value("\${true ? 'trueExp' : 'falseExp'}")
    lateinit var spel3: String
}

application.spel=${true ? trueExp : falseExp}
application.spel2=${2 > 1 ? a : b}

@SpringBootTest
class SpelTernaryApplicationTests {
    @Autowired
    lateinit var bean: SpelTernaryApplication

    @Test
    fun spelEvaluation() {
        val parser: ExpressionParser = SpelExpressionParser()
        val parserResult = parser.parseExpression("true ? 'trueExp' : 'falseExp'").getValue(String::class.java)

        println("parser: $parserResult")
        println("property: ${bean.spel}")
        println("property: ${bean.spel2}")
        println("@Value property: ${bean.spel3}")

        assert("trueExp" == parserResult) { "parser: $parserResult" }
        assert("trueExp" == bean.spel) { "property: ${bean.spel}" }
        assert("a" == bean.spel2) { "property: ${bean.spel2}" }
        assert("trueExp" == bean.spel3) { "@Value property: ${bean.spel3}" }
    }
}

produces

parser: trueExp property: falseExp property: b @Value property: 'falseExp'

property: falseExp java.lang.AssertionError: property: falseExp at com.example.spelternary.SpelTernaryApplicationTests.spelEvaluation(SpelTernaryApplicationTests.kt:26) [...]

example project: https://github.com/jackhammer2k/spring-spel-ternary-issue

Comment From: sbrannen

That's not a SpEL expression.

That's a property placeholder (${..}) with a "default value".

For a SpEL expression, you need to use the #{...} syntax. For further details, please consult the reference manual.