fix: ignore Kotlin DefaultConstructorMarker in BeanUtils#getParametersName (#34760)

Mismatch caused by DefaultConstructorMarker, which is now filtered out.
Signed-off-by: EmilSt <[email protected]>

Author: Emil-Stampfly-He

spring-beans/src/main/java/org/springframework/beans/BeanUtils.java

@@ -33,6 +33,7 @@
 import java.util.Set;
 
 import kotlin.jvm.JvmClassMappingKt;
+import kotlin.jvm.internal.DefaultConstructorMarker;
 import kotlin.reflect.KClass;
 import kotlin.reflect.KFunction;
 import kotlin.reflect.KParameter;
@@ -659,7 +660,13 @@ public static MethodParameter getWriteMethodParameter(PropertyDescriptor pd) {
 		ConstructorProperties cp = ctor.getAnnotation(ConstructorProperties.class);
 		@Nullable String[] paramNames = (cp != null ? cp.value() : parameterNameDiscoverer.getParameterNames(ctor));
 		Assert.state(paramNames != null, () -> "Cannot resolve parameter names for constructor " + ctor);
-		Assert.state(paramNames.length == ctor.getParameterCount(),
+
+		// The generated param "DefaultConstructorMarker" is used to avoid collision of signatures
+		// and should be filtered out
+		long realParamsCount = Arrays.stream(ctor.getParameters())
+				.filter(p -> !DefaultConstructorMarker.class.equals(p.getType()))
+				.count();
+		Assert.state(paramNames.length == realParamsCount,
 				() -> "Invalid number of parameter names: " + paramNames.length + " for constructor " + ctor);
 		return paramNames;
 	}

spring-beans/src/test/kotlin/org/springframework/beans/BeanUtilsKotlinTests.kt

@@ -157,6 +157,67 @@ class BeanUtilsKotlinTests {
 		assertThat(instance).isEqualTo(ConstructorWithNullablePrimitiveValueClass(null))
 	}
 
+	@Test
+	fun `getParameterNames filters out DefaultConstructorMarker with Foo`() {
+		val ctor = BeanUtils.findPrimaryConstructor(Foo::class.java)!!
+		val names = BeanUtils.getParameterNames(ctor)
+		assertThat(names).containsExactly("param1", "param2")
+	}
+
+
+	@Test
+	fun `getParameterNames filters out DefaultConstructorMarker with Bar`() {
+		val ctor = BeanUtils.findPrimaryConstructor(Bar::class.java)!!
+		val names = BeanUtils.getParameterNames(ctor)
+		assertThat(names).containsExactly("param1", "param2")
+	}
+
+	@Test
+	fun `getParameterNames filters out DefaultConstructorMarker with Baz`() {
+		val ctor = BeanUtils.findPrimaryConstructor(Baz::class.java)!!
+		val names = BeanUtils.getParameterNames(ctor)
+		assertThat(names).containsExactly("param1", "param2")
+	}
+
+	@Test
+	fun `getParameterNames filters out DefaultConstructorMarker with Qux`() {
+		val ctor = BeanUtils.findPrimaryConstructor(Qux::class.java)!!
+		val names = BeanUtils.getParameterNames(ctor)
+		assertThat(names).containsExactly("param1", "param2")
+	}
+
+	@Test
+	fun `getParameterNames filters out DefaultConstructorMarker with ConstructorWithValueClass`() {
+		val ctor = BeanUtils.findPrimaryConstructor(ConstructorWithValueClass::class.java)!!
+		assertThat(ctor).isNotNull()
+		val names = BeanUtils.getParameterNames(ctor)
+		assertThat(names).containsExactly("value")
+	}
+
+	@Test
+	fun `getParameterNames filters out DefaultConstructorMarker with ConstructorWithNullableValueClass`() {
+		val ctor = BeanUtils.findPrimaryConstructor(ConstructorWithNullableValueClass::class.java)!!
+		assertThat(ctor).isNotNull()
+		val names = BeanUtils.getParameterNames(ctor)
+		assertThat(names).containsExactly("value")
+	}
+
+	@Test
+	fun `getParameterNames filters out DefaultConstructorMarker with ConstructorWithPrimitiveValueClass`() {
+		val ctor = BeanUtils.findPrimaryConstructor(ConstructorWithPrimitiveValueClass::class.java)!!
+		assertThat(ctor).isNotNull()
+		val names = BeanUtils.getParameterNames(ctor)
+		assertThat(names).containsExactly("value")
+	}
+
+	@Test
+	fun `getParameterNames filters out DefaultConstructorMarker with ConstructorWithNullablePrimitiveValueClass`() {
+		val ctor = BeanUtils.findPrimaryConstructor(ConstructorWithNullablePrimitiveValueClass::class.java)!!
+		assertThat(ctor).isNotNull()
+		val names = BeanUtils.getParameterNames(ctor)
+		assertThat(names).containsExactly("value")
+	}
+
 
 	class Foo(val param1: String, val param2: Int)