Add multi-unit DurationFormat.Style for duration parsing/printing

This adds the COMPOSITE style, which allows multiple segments each
similar to the SIMPLE style.

See gh-30396
Closes gh-33262

spring-context/src/test/kotlin/org/springframework/format/datetime/standard/DurationFormatterUtilsKotlinTests.kt

@@ -0,0 +1,60 @@
+/*
+ * Copyright 2002-2024 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.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.format.datetime.standard
+
+import org.assertj.core.api.Assertions
+import org.junit.jupiter.api.Test
+import org.springframework.format.annotation.DurationFormat
+import kotlin.time.Duration
+import kotlin.time.toKotlinDuration
+
+/**
+ * Tests for [DurationFormatterUtils] compatibility with Kotlin.
+ *
+ * @author Simon Baslé
+ */
+class DurationFormatterUtilsKotlinTests {
+
+	@Test
+	fun `Composite style parses Kotlin toString() with seconds resolution`() {
+		val kotlinString = "-(1d 2h 34m 57s)"
+		val duration = Duration.parse(kotlinString)
+
+		val parseResult = DurationFormatterUtils.parse(kotlinString, DurationFormat.Style.COMPOSITE)
+			.toKotlinDuration()
+
+		Assertions.assertThat(parseResult).isEqualTo(duration)
+	}
+
+	@Test
+	fun `Composite style fails Kotlin toString() with sub-second resolution`() {
+		val kotlinString = "-(1d 2h 34m 57.028003002s)"
+
+		Assertions.assertThatException().isThrownBy {
+			DurationFormatterUtils.parse(kotlinString, DurationFormat.Style.COMPOSITE) }
+			.withMessage("'$kotlinString' is not a valid composite duration")
+	}
+
+	@Test
+	fun `Detect and parse fails Kotlin toString() with sub-second resolution`() {
+		val kotlinString = "-(1d 2h 34m 57.028003002s)"
+
+		Assertions.assertThatException().isThrownBy { DurationFormatterUtils.detectAndParse(kotlinString) }
+			.withMessage("'$kotlinString' is not a valid duration, cannot detect any known style")
+	}
+
+}