Prefer mapping without version for unversioned request

Closes gh-35237

Author: rstoyanchev

spring-webflux/src/main/java/org/springframework/web/reactive/result/condition/VersionRequestCondition.java

@@ -128,7 +128,9 @@ else if (this.version != null && otherVersion != null) {
 			return (-1 * compareVersions(this.version, otherVersion));
 		}
 		else {
-			return (this.version != null ? -1 : 1);
+			// Prefer mapping without version for unversioned request
+			Comparable<?> version = exchange.getAttribute(HandlerMapping.API_VERSION_ATTRIBUTE);
+			return (version != null ? (this.version != null ? -1 : 1) : (this.version != null ? 1 : -1));
 		}
 	}
 

spring-webflux/src/test/java/org/springframework/web/reactive/result/condition/VersionRequestConditionTests.java

@@ -18,6 +18,7 @@
 
 import java.util.Arrays;
 import java.util.List;
+import java.util.stream.Stream;
 
 import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.BeforeEach;
@@ -159,6 +160,15 @@ void noRequestVersion() {
 		condition.handleMatch(exchange);
 	}
 
+	@Test
+	void compareWithoutRequestVersion() {
+		VersionRequestCondition condition = Stream.of(condition("1.1"), condition("1.2"), emptyCondition())
+				.min((c1, c2) -> c1.compareTo(c2, exchange()))
+				.get();
+
+		assertThat(condition).isEqualTo(emptyCondition());
+	}
+
 	private VersionRequestCondition condition(String v) {
 		this.strategy.addSupportedVersion(v.endsWith("+") ? v.substring(0, v.length() - 1) : v);
 		return new VersionRequestCondition(v, this.strategy);

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/condition/VersionRequestCondition.java

@@ -127,7 +127,9 @@ else if (this.version != null && otherVersion != null) {
 			return (-1 * compareVersions(this.version, otherVersion));
 		}
 		else {
-			return (this.version != null ? -1 : 1);
+			// Prefer mapping without version for unversioned request
+			Comparable<?> version = (Comparable<?>) request.getAttribute(HandlerMapping.API_VERSION_ATTRIBUTE);
+			return (version != null ? (this.version != null ? -1 : 1) : (this.version != null ? 1 : -1));
 		}
 	}
 

spring-webmvc/src/test/java/org/springframework/web/servlet/mvc/condition/VersionRequestConditionTests.java

@@ -18,6 +18,7 @@
 
 import java.util.Arrays;
 import java.util.List;
+import java.util.stream.Stream;
 
 import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.BeforeEach;
@@ -146,6 +147,15 @@ private void testCompare(String expected, String... versions) {
 		assertThat(list.get(0)).isEqualTo(condition(expected));
 	}
 
+	@Test
+	void compareWithoutRequestVersion() {
+		VersionRequestCondition condition = Stream.of(condition("1.1"), condition("1.2"), emptyCondition())
+				.min((c1, c2) -> c1.compareTo(c2, new MockHttpServletRequest()))
+				.get();
+
+		assertThat(condition).isEqualTo(emptyCondition());
+	}
+
 	@Test // gh-35236
 	void noRequestVersion() {
 		MockHttpServletRequest request = new MockHttpServletRequest("GET", "/path");