BeanUtils.getParameterNames fails for Kotlin data classes

[bclozel]

While working on spring-projects/spring-graphql#1186, I have noticed that BeanUtils.getParameterNames(Constructor) checks that the number of detected parameter names is equal to the number of constructor arguments detected via Java reflection.

In the case of Kotlin data classes, there is an additional kotlin.jvm.internal.DefaultConstructorMarker constructor argument which fails with the following:

Invalid number of parameter names: 1 for constructor public org.springframework.beans.BeanUtilsKotlinTests$ConstructorWithValueClass(java.lang.String,kotlin.jvm.internal.DefaultConstructorMarker)
java.lang.IllegalStateException: Invalid number of parameter names: 1 for constructor public org.springframework.beans.BeanUtilsKotlinTests$ConstructorWithValueClass(java.lang.String,kotlin.jvm.internal.DefaultConstructorMarker)

We can reproduce this with:

@Test
fun `Detect constructor parameter names`() {
	val constructor = BeanUtils.getResolvableConstructor(ConstructorWithValueClass::class.java)
	BeanUtils.getParameterNames(constructor)
}

data class ConstructorWithValueClass(val value: ValueClass)

@JvmInline
value class ValueClass(private val value: String)