Ignore parameters when checking if */* is accepted

Previously the parameters were not ignored so */*;q=0.8 was not
identified as accepting */*. As a result, the most recent producible
content type was returned rather than the default.

This commit updates the argument resolver to ignore parameters.
The default content type is now produced in response to a request
that accepts */*, irrespective of its parameters.

Fixes gh-28446

spring-boot-project/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/endpoint/ProducibleOperationArgumentResolver.java

@@ -65,7 +65,7 @@ private Enum<? extends Producible<?>> resolveProducible(Class<Enum<? extends Pro
 		Enum<? extends Producible<?>> result = null;
 		for (String accept : accepts) {
 			for (String mimeType : MimeTypeUtils.tokenize(accept)) {
-				result = mostRecent(result, forMimeType(values, mimeType));
+				result = mostRecent(result, forMimeType(values, MimeTypeUtils.parseMimeType(mimeType)));
 			}
 		}
 		return result;
@@ -78,14 +78,10 @@ private Enum<? extends Producible<?>> mostRecent(Enum<? extends Producible<?>> e
 		return (candidateOrdinal > existingOrdinal) ? candidate : existing;
 	}
 
-	private Enum<? extends Producible<?>> forMimeType(List<Enum<? extends Producible<?>>> values, String mimeType) {
-		if ("*/*".equals(mimeType)) {
+	private Enum<? extends Producible<?>> forMimeType(List<Enum<? extends Producible<?>>> values, MimeType mimeType) {
+		if (mimeType.isWildcardType() && mimeType.isWildcardSubtype()) {
 			return getDefaultValue(values);
 		}
-		return forMimeType(values, MimeTypeUtils.parseMimeType(mimeType));
-	}
-
-	private Enum<? extends Producible<?>> forMimeType(List<Enum<? extends Producible<?>>> values, MimeType mimeType) {
 		for (Enum<? extends Producible<?>> candidate : values) {
 			if (mimeType.isCompatibleWith(((Producible<?>) candidate).getProducedMimeType())) {
 				return candidate;

spring-boot-project/spring-boot-actuator/src/test/java/org/springframework/boot/actuate/metrics/export/prometheus/PrometheusScrapeEndpointIntegrationTests.java

@@ -41,12 +41,25 @@ class PrometheusScrapeEndpointIntegrationTests {
 
 	@WebEndpointTest
 	void scrapeHasContentTypeText004ByDefault(WebTestClient client) {
+		String expectedContentType = TextFormat.CONTENT_TYPE_004;
+		assertThat(TextFormat.chooseContentType(null)).isEqualTo(expectedContentType);
 		client.get().uri("/actuator/prometheus").exchange().expectStatus().isOk().expectHeader()
-				.contentType(MediaType.parseMediaType(TextFormat.CONTENT_TYPE_004)).expectBody(String.class)
+				.contentType(MediaType.parseMediaType(expectedContentType)).expectBody(String.class)
 				.value((body) -> assertThat(body).contains("counter1_total").contains("counter2_total")
 						.contains("counter3_total"));
 	}
 
+	@WebEndpointTest
+	void scrapeHasContentTypeText004ByDefaultWhenClientAcceptsWildcardWithParameter(WebTestClient client) {
+		String expectedContentType = TextFormat.CONTENT_TYPE_004;
+		String accept = "*/*;q=0.8";
+		assertThat(TextFormat.chooseContentType(accept)).isEqualTo(expectedContentType);
+		client.get().uri("/actuator/prometheus").accept(MediaType.parseMediaType(accept)).exchange().expectStatus()
+				.isOk().expectHeader().contentType(MediaType.parseMediaType(expectedContentType))
+				.expectBody(String.class).value((body) -> assertThat(body).contains("counter1_total")
+						.contains("counter2_total").contains("counter3_total"));
+	}
+
 	@WebEndpointTest
 	void scrapeCanProduceOpenMetrics100(WebTestClient client) {
 		MediaType openMetrics = MediaType.parseMediaType(TextFormat.CONTENT_TYPE_OPENMETRICS_100);