Combined, empty RequestMapping matches both "" and "/"

Closes gh-29625

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2020 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.
@@ -48,6 +48,9 @@ public final class PatternsRequestCondition extends AbstractRequestCondition<Pat
 
 	private static final Set<String> EMPTY_PATH = Collections.singleton("");
 
+	private static final SortedSet<PathPattern> ROOT_PATH_PATTERNS =
+			new TreeSet<>(List.of(new PathPatternParser().parse(""), new PathPatternParser().parse("/")));
+
 
 	private final SortedSet<PathPattern> patterns;
 
@@ -109,19 +112,18 @@ public final class PatternsRequestCondition extends AbstractRequestCondition<Pat
 	}
 
 	/**
-	 * Returns a new instance with URL patterns from the current instance ("this") and
-	 * the "other" instance as follows:
+	 * Combine the patterns of the current and of the other instances as follows:
 	 * <ul>
-	 * <li>If there are patterns in both instances, combine the patterns in "this" with
-	 * the patterns in "other" using {@link PathPattern#combine(PathPattern)}.
-	 * <li>If only one instance has patterns, use them.
-	 * <li>If neither instance has patterns, use an empty String (i.e. "").
+	 * <li>If only one instance has patterns, use those.
+	 * <li>If both have patterns, combine patterns from "this" instance with
+	 * patterns from the other instance via {@link PathPattern#combine(PathPattern)}.
+	 * <li>If neither has patterns, use {@code ""} and {@code "/"} as root path patterns.
 	 * </ul>
 	 */
 	@Override
 	public PatternsRequestCondition combine(PatternsRequestCondition other) {
 		if (isEmptyPathMapping() && other.isEmptyPathMapping()) {
-			return this;
+			return new PatternsRequestCondition(ROOT_PATH_PATTERNS);
 		}
 		else if (other.isEmptyPathMapping()) {
 			return this;

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 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.
@@ -52,8 +52,8 @@ public class PatternsRequestConditionTests {
 		PatternsRequestCondition c2 = new PatternsRequestCondition();
 		PatternsRequestCondition c3 = c1.combine(c2);
 
-		assertThat(c3).isSameAs(c1);
 		assertThat(c1.getPatterns()).isSameAs(c2.getPatterns()).containsExactly(this.parser.parse(""));
+		assertThat(c3.toString()).isEqualTo("[/ || ]");
 	}
 
 	@Test

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 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.
@@ -73,7 +73,7 @@ public class RequestMappingInfoTests {
 		assertThat(info.getCustomCondition()).isSameAs(anotherInfo.getCustomCondition());
 
 		RequestMappingInfo result = info.combine(anotherInfo);
-		assertThat(info.getPatternsCondition()).isSameAs(result.getPatternsCondition());
+		assertThat(result.getPatternsCondition().toString()).isEqualTo("[/ || ]");
 		assertThat(info.getMethodsCondition()).isSameAs(result.getMethodsCondition());
 		assertThat(info.getParamsCondition()).isSameAs(result.getParamsCondition());
 		assertThat(info.getHeadersCondition()).isSameAs(result.getHeadersCondition());

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2020 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.
@@ -20,6 +20,7 @@ import java.util.Collection;
 import java.util.Collections;
 import java.util.HashSet;
 import java.util.Iterator;
+import java.util.List;
 import java.util.Set;
 import java.util.SortedSet;
 import java.util.TreeSet;
@@ -52,6 +53,9 @@ public final class PathPatternsRequestCondition extends AbstractRequestCondition
 
 	private static final Set<String> EMPTY_PATH = Collections.singleton("");
 
+	private static final SortedSet<PathPattern> ROOT_PATH_PATTERNS =
+			new TreeSet<>(List.of(new PathPatternParser().parse(""), new PathPatternParser().parse("/")));
+
 
 	private final SortedSet<PathPattern> patterns;
 
@@ -146,20 +150,18 @@ public final class PathPatternsRequestCondition extends AbstractRequestCondition
 	}
 
 	/**
-	 * Returns a new instance with URL patterns from the current instance
-	 * ("this") and the "other" instance as follows:
+	 * Combine the patterns of the current and of the other instances as follows:
 	 * <ul>
-	 * <li>If there are patterns in both instances, combine the patterns in
-	 * "this" with the patterns in "other" using
-	 * {@link PathPattern#combine(PathPattern)}.
-	 * <li>If only one instance has patterns, use them.
-	 * <li>If neither instance has patterns, use an empty String (i.e. "").
+	 * <li>If only one instance has patterns, use those.
+	 * <li>If both have patterns, combine patterns from "this" instance with
+	 * patterns from the other instance via {@link PathPattern#combine(PathPattern)}.
+	 * <li>If neither has patterns, use {@code ""} and {@code "/"} as root path patterns.
 	 * </ul>
 	 */
 	@Override
 	public PathPatternsRequestCondition combine(PathPatternsRequestCondition other) {
 		if (isEmptyPathMapping() && other.isEmptyPathMapping()) {
-			return this;
+			return new PathPatternsRequestCondition(ROOT_PATH_PATTERNS);
 		}
 		else if (other.isEmptyPathMapping()) {
 			return this;

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 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.
@@ -51,6 +51,8 @@ public class PatternsRequestCondition extends AbstractRequestCondition<PatternsR
 
 	private final static Set<String> EMPTY_PATH_PATTERN = Collections.singleton("");
 
+	private final static String[] ROOT_PATH_PATTERNS = new String[] {"", "/"};
+
 
 	private final Set<String> patterns;
 
@@ -227,19 +229,18 @@ public class PatternsRequestCondition extends AbstractRequestCondition<PatternsR
 	}
 
 	/**
-	 * Returns a new instance with URL patterns from the current instance ("this") and
-	 * the "other" instance as follows:
+	 * Combine the patterns of the current and of the other instances as follows:
 	 * <ul>
-	 * <li>If there are patterns in both instances, combine the patterns in "this" with
-	 * the patterns in "other" using {@link PathMatcher#combine(String, String)}.
-	 * <li>If only one instance has patterns, use them.
-	 * <li>If neither instance has patterns, use an empty String (i.e. "").
+	 * <li>If only one instance has patterns, use those.
+	 * <li>If both have patterns, combine patterns from "this" instance with
+	 * patterns from the other instance via {@link PathMatcher#combine(String, String)}.
+	 * <li>If neither has patterns, use {@code ""} and {@code "/"} as root path patterns.
 	 * </ul>
 	 */
 	@Override
 	public PatternsRequestCondition combine(PatternsRequestCondition other) {
 		if (isEmptyPathMapping() && other.isEmptyPathMapping()) {
-			return this;
+			return new PatternsRequestCondition(ROOT_PATH_PATTERNS);
 		}
 		else if (other.isEmptyPathMapping()) {
 			return this;

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 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.
@@ -59,8 +59,8 @@ public class PathPatternsRequestConditionTests {
 		PathPatternsRequestCondition c2 = createCondition();
 		PathPatternsRequestCondition c3 = c1.combine(c2);
 
-		assertThat(c3).isSameAs(c1);
 		assertThat(c1.getPatternValues()).isSameAs(c2.getPatternValues()).containsExactly("");
+		assertThat(c3.getPatternValues()).containsExactly("", "/");
 	}
 
 	@Test

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2020 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.
@@ -58,8 +58,8 @@ class PatternsRequestConditionTests {
 		PatternsRequestCondition c2 = new PatternsRequestCondition();
 		PatternsRequestCondition c3 = c1.combine(c2);
 
-		assertThat(c3).isSameAs(c1);
 		assertThat(c1.getPatterns()).isSameAs(c2.getPatterns()).containsExactly("");
+		assertThat(c3.getPatterns()).containsExactly("", "/");
 	}
 
 	@Test

spring-webmvc/src/test/java/org/springframework/web/servlet/mvc/method/RequestMappingInfoTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 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.
@@ -77,7 +77,7 @@ class RequestMappingInfoTests {
 		assertThat(info.getCustomCondition()).isSameAs(anotherInfo.getCustomCondition());
 
 		RequestMappingInfo result = info.combine(anotherInfo);
-		assertThat(info.getActivePatternsCondition()).isSameAs(result.getActivePatternsCondition());
+		assertThat(result.getPatternValues()).containsExactly("", "/");
 		assertThat(info.getMethodsCondition()).isSameAs(result.getMethodsCondition());
 		assertThat(info.getParamsCondition()).isSameAs(result.getParamsCondition());
 		assertThat(info.getHeadersCondition()).isSameAs(result.getHeadersCondition());