Support instantiating Kotlin classes with optional parameters

This commit updates BeanUtils class in order to add Kotlin optional
parameters with default values support to the immutable data classes
support introduced by SPR-15199.

Issue: SPR-15673

spring-beans/src/test/java/org/springframework/beans/BeanUtilsTests.java

@@ -18,6 +18,7 @@ package org.springframework.beans;
 
 import java.beans.Introspector;
 import java.beans.PropertyDescriptor;
+import java.lang.reflect.Constructor;
 import java.lang.reflect.Method;
 import java.util.ArrayList;
 import java.util.List;
@@ -274,6 +275,23 @@ public class BeanUtilsTests {
 			}
 		}
 	}
+	
+	@Test 
+	public void testFindDefaultConstructorAndInstantiate() {
+		Constructor<Bean> ctor = BeanUtils.findPrimaryConstructor(Bean.class);
+		assertNotNull(ctor);
+		Bean bean = BeanUtils.instantiateClass(ctor);
+		assertNotNull(bean);
+	}
+
+	@Test
+	public void testFindSingleNonDefaultConstructorAndInstantiate() {
+		Constructor<BeanWithSingleNonDefaultConstructor> ctor = BeanUtils.findPrimaryConstructor(BeanWithSingleNonDefaultConstructor.class);
+		assertNotNull(ctor);
+		BeanWithSingleNonDefaultConstructor bean = BeanUtils.instantiateClass(ctor, "foo");
+		assertNotNull(bean);
+		assertEquals("foo", bean.getName());
+	}
 
 	private void assertSignatureEquals(Method desiredMethod, String signature) {
 		assertEquals(desiredMethod, BeanUtils.resolveSignature(signature, MethodSignatureBean.class));
@@ -444,5 +462,18 @@ public class BeanUtilsTests {
 			value = aValue;
 		}
 	}
+	
+	private static class BeanWithSingleNonDefaultConstructor {
+		
+		private final String name;
+
+		public BeanWithSingleNonDefaultConstructor(String name) {
+			this.name = name;
+		}
+
+		public String getName() {
+			return name;
+		}
+	}
 
 }