Refine null handling in UriComponentsBuilder#query

Closes gh-35629

Author: rstoyanchev

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

@@ -144,9 +144,10 @@ public interface UriBuilder {
 UriBuilder pathSegment(String... pathSegments) throws IllegalArgumentException;
 
 /**
- * Parse the given query string into query parameters where parameters are
- * separated with {@code '&'} and their values, if any, with {@code '='}.
- * The query may contain URI template variables.
+ * Parse the given query string into query parameters, and append them to
+ * the query string. Query parameters are separated with {@code '&'} while
+ * their values, if any, are separated with {@code '='}. The query string
+ * may contain URI template variables.
  * <p><strong>Note: </strong> please, review the Javadoc of
  * {@link #queryParam(String, Object...)} for further notes on the treatment
  * and encoding of individual query parameters.

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

@@ -426,7 +426,9 @@ private UriComponentsBuilder rfcUriRecord(RfcUriParser.UriRecord record) {
 if (record.path() != null) {
 path(record.path());
 }
-query(record.query());
+if (record.query() != null) {
+query(record.query());
+}
 }
 fragment(record.fragment());
 return this;
@@ -453,7 +455,9 @@ private UriComponentsBuilder whatWgUrlRecord(WhatWgUrlParser.UrlRecord record) {
 port(record.portString());
 }
 path(record.path().toString());
-query(record.query());
+if (record.query() != null) {
+query(record.query());
+}
 }
 if (StringUtils.hasText(record.fragment())) {
 fragment(record.fragment());
@@ -541,8 +545,8 @@ public UriComponentsBuilder replacePath(@Nullable String path) {
 }
 
 @Override
-public UriComponentsBuilder query(@Nullable String query) {
-if (query != null) {
+public UriComponentsBuilder query(String query) {
+if (StringUtils.hasText(query)) {
 Matcher matcher = QUERY_PARAM_PATTERN.matcher(query);
 while (matcher.find()) {
 String name = matcher.group(1);

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

@@ -479,20 +479,18 @@ void replacePath(ParserType parserType) {
 
 @ParameterizedTest
 @EnumSource
-void query(final ParserType parserType) {
-final UriComponents uriComponents = UriComponentsBuilder.fromUriString("https://example.com/foo?foo=bar", parserType)
-.query("baz=qux")
-.build();
-assertThat(uriComponents.getQueryParams()).isEqualTo(Map.of("foo", List.of("bar"), "baz", List.of("qux")));
+void query(ParserType parserType) {
+String url = "https://example.com/foo?foo=bar";
+UriComponents uric = UriComponentsBuilder.fromUriString(url, parserType).query("baz=qux").build();
+assertThat(uric.getQueryParams()).isEqualTo(Map.of("foo", List.of("bar"), "baz", List.of("qux")));
 }
 
 @ParameterizedTest
-@EnumSource
-void queryWithNullDoesRetainQueryParameters(final ParserType parserType) {
-final UriComponents uriComponents = UriComponentsBuilder.fromUriString("https://example.com/foo?foo=bar", parserType)
-.query(null)
-.build();
-assertThat(uriComponents.getQueryParams()).isEqualTo(Map.of("foo", List.of("bar")));
+@EnumSource // gh-35628
+void queryWithNull(ParserType parserType) {
+String url = "https://example.com/foo?foo=bar";
+UriComponents uric = UriComponentsBuilder.fromUriString(url, parserType).query(null).build();
+assertThat(uric.getQueryParams()).isEqualTo(Map.of("foo", List.of("bar")));
 }
 
 @ParameterizedTest