Add Kotlin extensions for Cache and CacheManager

See gh-23927

spring-context/src/test/kotlin/org/springframework/cache/CacheExtensionsTest.kt

@@ -0,0 +1,31 @@
+package org.springframework.cache
+
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Test
+import org.springframework.cache.concurrent.ConcurrentMapCacheManager
+
+class CacheExtensionsTest {
+
+	@Test
+	fun `Check inline get variant`() {
+		val cache = createCache()
+		cache.put("k", "v")
+		assertEquals("v", cache.get<String>("k"))
+	}
+
+	@Test
+	fun `Check operator get variant`() {
+		val cache = createCache()
+		cache.put("k", "v")
+		assertEquals("v", cache["k"]?.get() as String?)
+	}
+
+	@Test
+	fun `Check operator set variant`() {
+		val cache = createCache()
+		cache["k"] = "v"
+		assertEquals("v", cache.get("k", String::class.java))
+	}
+
+	private fun createCache(cacheName: String = "c"): Cache = ConcurrentMapCacheManager(cacheName).getCache(cacheName)!!
+}

spring-context/src/test/kotlin/org/springframework/cache/CacheManagerExtensionsTest.kt

@@ -0,0 +1,16 @@
+package org.springframework.cache
+
+import org.junit.jupiter.api.Assertions.assertNotEquals
+import org.junit.jupiter.api.Test
+import org.springframework.cache.concurrent.ConcurrentMapCacheManager
+
+class CacheManagerExtensionsTest {
+
+	@Test
+	fun `Check operator get variant`() {
+		val cm = createCacheManager("c")
+		assertNotEquals(null, cm["c"])
+	}
+
+	private fun createCacheManager(cacheName: String = "c"): CacheManager = ConcurrentMapCacheManager(cacheName)
+}