Add extension for PropertyResolver#getProperty(String, Class<T>, T)

Allows Kotlin caller to get a non-nullable property,
using a default value when the property is not set.
A method already exists on PropertyResolver which does this,
but takes a Class parameter.
The extension method can eliminate the parameter via reified type,
similar to the other extension methods which exist already.

Closes gh-31523

spring-core/src/main/kotlin/org/springframework/core/env/PropertyResolverExtensions.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -42,6 +42,16 @@ operator fun PropertyResolver.get(key: String) : String? = getProperty(key)
 inline fun <reified T> PropertyResolver.getProperty(key: String) : T? =
 		getProperty(key, T::class.java)
 
+/**
+ * Extension for [PropertyResolver.getProperty] providing a `getProperty<Foo>(...)`
+ * variant returning a non-nullable `Foo` with a default value.
+ *
+ * @author John Burns
+ * @since 6.1
+ */
+inline fun <reified T : Any> PropertyResolver.getProperty(key: String, default: T) : T =
+	getProperty(key, T::class.java, default)
+
 /**
  * Extension for [PropertyResolver.getRequiredProperty] providing a
  * `getRequiredProperty<Foo>(...)` variant.

spring-core/src/test/kotlin/org/springframework/core/env/PropertyResolverExtensionsKotlinTests.kt

@@ -19,6 +19,7 @@ package org.springframework.core.env
 import io.mockk.every
 import io.mockk.mockk
 import io.mockk.verify
+import org.assertj.core.api.Assertions.assertThat
 import org.junit.jupiter.api.Test
 
 /**
@@ -44,6 +45,13 @@ class PropertyResolverExtensionsKotlinTests {
 		verify { propertyResolver.getProperty("name", String::class.java) }
 	}
 
+	@Test
+	fun `getProperty with default extension`() {
+		every { propertyResolver.getProperty("name", String::class.java, "default") } returns "default"
+		assertThat(propertyResolver.getProperty<String>("name", "default")).isEqualTo("default")
+		verify { propertyResolver.getProperty("name", String::class.java, "default") }
+	}
+
 	@Test
 	fun `getRequiredProperty extension`() {
 		every { propertyResolver.getRequiredProperty("name", String::class.java) } returns "foo"