Fix UriComponentsBuilder.fromUriString parsing error

This commit fixes cases where part of the URI was mistaken for the
userinfo when:
* the URI did not contain any path
* the query string contained the "@"

Issue: SPR-11964

spring-web/src/main/java/org/springframework/web/util/UriComponentsBuilder.java

@@ -62,7 +62,7 @@ public class UriComponentsBuilder {
 
 	private static final String HTTP_PATTERN = "(?i)(http|https):";
 
-	private static final String USERINFO_PATTERN = "([^@/]*)";
+	private static final String USERINFO_PATTERN = "([^@\\[/?#]*)";
 
 	private static final String HOST_IPV4_PATTERN = "[^\\[/?#:]*";
 

spring-web/src/test/java/org/springframework/web/util/UriComponentsBuilderTests.java

@@ -26,6 +26,7 @@ import org.junit.Test;
 
 import org.springframework.util.LinkedMultiValueMap;
 import org.springframework.util.MultiValueMap;
+import org.springframework.util.StringUtils;
 
 import static org.hamcrest.Matchers.*;
 import static org.junit.Assert.*;
@@ -216,6 +217,17 @@ public class UriComponentsBuilderTests {
 		assertEquals("[::192.168.1.1]", resultIPv4compatible.getHost());
 	}
 
+	// SPR-11970
+
+	@Test
+	public void fromUriStringNoPathWithReservedCharInQuery() {
+		UriComponents result = UriComponentsBuilder.fromUriString("http://example.com?foo=bar@baz").build();
+		assertTrue(StringUtils.isEmpty(result.getUserInfo()));
+		assertEquals("example.com", result.getHost());
+		assertTrue(result.getQueryParams().containsKey("foo"));
+		assertEquals("bar@baz", result.getQueryParams().getFirst("foo"));
+	}
+
 	@Test
 	public void path() throws URISyntaxException {
 		UriComponentsBuilder builder = UriComponentsBuilder.fromPath("/foo/bar");