PathVariable consistently reflects value up to 1st ";"

Given "/{foo}" and "/a=42;c=b", previously that would be treated as a
sequence of matrix vars with an empty path variable. After the change
the path variable "foo" is "a=42".

This should be ok for backawards compatibility since it's unlikely for
anything to rely on an empty path variable.

Issue: SPR-11897

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/RequestMappingInfoHandlerMapping.java

@@ -149,20 +149,23 @@ public abstract class RequestMappingInfoHandlerMapping extends AbstractHandlerMe
 
 		Map<String, MultiValueMap<String, String>> result = new LinkedHashMap<>();
 		uriVariables.forEach((uriVarKey, uriVarValue) -> {
+
 			int equalsIndex = uriVarValue.indexOf('=');
 			if (equalsIndex == -1) {
 				return;
 			}
 
-			String matrixVariables;
-
 			int semicolonIndex = uriVarValue.indexOf(';');
-			if ((semicolonIndex == -1) || (semicolonIndex == 0) || (equalsIndex < semicolonIndex)) {
+			if (semicolonIndex != -1 && semicolonIndex != 0) {
+				uriVariables.put(uriVarKey, uriVarValue.substring(0, semicolonIndex));
+			}
+
+			String matrixVariables;
+			if (semicolonIndex == -1 || semicolonIndex == 0 || equalsIndex < semicolonIndex) {
 				matrixVariables = uriVarValue;
 			}
 			else {
 				matrixVariables = uriVarValue.substring(semicolonIndex + 1);
-				uriVariables.put(uriVarKey, uriVarValue.substring(0, semicolonIndex));
 			}
 
 			MultiValueMap<String, String> vars = WebUtils.parseMatrixVariables(matrixVariables);

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

@@ -311,6 +311,7 @@ public class RequestMappingInfoHandlerMappingTests {
 		MultiValueMap<String, String> matrixVariables;
 		Map<String, String> uriVariables;
 
+		// URI var parsed into path variable + matrix params..
 		request = new MockHttpServletRequest();
 		handleMatch(request, "/{cars}", "/cars;colors=red,blue,green;year=2012");
 
@@ -322,6 +323,7 @@ public class RequestMappingInfoHandlerMappingTests {
 		assertEquals("2012", matrixVariables.getFirst("year"));
 		assertEquals("cars", uriVariables.get("cars"));
 
+		// URI var with regex for path variable, and URI var for matrix params..
 		request = new MockHttpServletRequest();
 		handleMatch(request, "/{cars:[^;]+}{params}", "/cars;colors=red,blue,green;year=2012");
 
@@ -334,6 +336,7 @@ public class RequestMappingInfoHandlerMappingTests {
 		assertEquals("cars", uriVariables.get("cars"));
 		assertEquals(";colors=red,blue,green;year=2012", uriVariables.get("params"));
 
+		// URI var with regex for path variable, and (empty) URI var for matrix params..
 		request = new MockHttpServletRequest();
 		handleMatch(request, "/{cars:[^;]+}{params}", "/cars");
 
@@ -343,6 +346,18 @@ public class RequestMappingInfoHandlerMappingTests {
 		assertNull(matrixVariables);
 		assertEquals("cars", uriVariables.get("cars"));
 		assertEquals("", uriVariables.get("params"));
+
+		// SPR-11897
+		request = new MockHttpServletRequest();
+		handleMatch(request, "/{foo}", "/a=42;b=c");
+
+		matrixVariables = getMatrixVariables(request, "foo");
+		uriVariables = getUriTemplateVariables(request);
+
+		assertNotNull(matrixVariables);
+		assertEquals("42", matrixVariables.getFirst("a"));
+		assertEquals("c", matrixVariables.getFirst("b"));
+		assertEquals("a=42", uriVariables.get("foo"));
 	}
 
 	@Test // SPR-10140, SPR-16867