MockMvc handles param without values

Closes gh-35210

spring-test/src/main/java/org/springframework/test/web/servlet/request/AbstractMockHttpServletRequestBuilder.java

@@ -372,6 +372,10 @@ public abstract class AbstractMockHttpServletRequestBuilder<B extends AbstractMo
 	 * @param values one or more values
 	 */
 	public B param(String name, String... values) {
+		if (values.length == 0) {
+			this.parameters.computeIfAbsent(name, k -> new ArrayList<>());
+			return self();
+		}
 		addToMultiValueMap(this.parameters, name, values);
 		return self();
 	}
@@ -821,11 +825,8 @@ public abstract class AbstractMockHttpServletRequestBuilder<B extends AbstractMo
 		}
 		addRequestParams(request, UriComponentsBuilder.fromUri(uri).build().getQueryParams());
 
-		this.parameters.forEach((name, values) -> {
-			for (String value : values) {
-				request.addParameter(name, value);
-			}
-		});
+		this.parameters.forEach((name, values) ->
+				request.setParameter(name, values.toArray(new String[0])));
 
 		if (!this.formFields.isEmpty()) {
 			if (this.content != null && this.content.length > 0) {

spring-test/src/test/java/org/springframework/test/web/servlet/request/MockHttpServletRequestBuilderTests.java

@@ -263,6 +263,16 @@ class MockHttpServletRequestBuilderTests {
 		assertThat(request.getQueryString()).isEqualTo("foo=bar&foo=baz");
 	}
 
+	@Test // gh-35210
+	void queryParameterWithoutValues() {
+		this.builder = new MockHttpServletRequestBuilder(GET).uri("/");
+		this.builder.queryParam("foo");
+		MockHttpServletRequest request = this.builder.buildRequest(this.servletContext);
+
+		assertThat(request.getQueryString()).isEqualTo("foo");
+		assertThat(request.getParameterMap().get("foo")).containsExactly();
+	}
+
 	@Test
 	void queryParameterMap() {
 		this.builder = new MockHttpServletRequestBuilder(GET).uri("/");