Upgrade to Jetty 12.1.6

Closes gh-49133

module/spring-boot-jetty/src/main/java/org/springframework/boot/jetty/autoconfigure/JettyVirtualThreadsWebServerFactoryCustomizer.java

@@ -21,7 +21,6 @@ import org.eclipse.jetty.util.thread.VirtualThreadPool;
 import org.jspecify.annotations.Nullable;
 
 import org.springframework.boot.jetty.ConfigurableJettyWebServerFactory;
-import org.springframework.boot.jetty.autoconfigure.JettyServerProperties.Threads;
 import org.springframework.boot.web.server.WebServerFactoryCustomizer;
 import org.springframework.core.Ordered;
 import org.springframework.util.Assert;
@@ -62,16 +61,21 @@ public class JettyVirtualThreadsWebServerFactoryCustomizer
 	@Override
 	public void customize(ConfigurableJettyWebServerFactory factory) {
 		Assert.state(VirtualThreads.areSupported(), "Virtual threads are not supported");
-		VirtualThreadPool virtualThreadPool = new VirtualThreadPool();
+		Integer maxTasks = getMaxTasks();
+		VirtualThreadPool virtualThreadPool = (maxTasks != null) ? new VirtualThreadPool(maxTasks)
+				: new VirtualThreadPool();
 		virtualThreadPool.setName("jetty-");
-		if (this.serverProperties != null) {
-			Threads properties = this.serverProperties.getThreads();
-			int maxThreadCount = (properties.getMax() > 0) ? properties.getMax() : 200;
-			virtualThreadPool.setMaxThreads(maxThreadCount);
-		}
 		factory.setThreadPool(virtualThreadPool);
 	}
 
+	private @Nullable Integer getMaxTasks() {
+		if (this.serverProperties == null) {
+			return null;
+		}
+		Integer maxThreads = this.serverProperties.getThreads().getMax();
+		return (maxThreads > 0) ? maxThreads : null;
+	}
+
 	@Override
 	public int getOrder() {
 		return JettyWebServerFactoryCustomizer.ORDER + 1;

module/spring-boot-jetty/src/test/java/org/springframework/boot/jetty/autoconfigure/JettyVirtualThreadsWebServerFactoryCustomizerTests.java

@@ -48,7 +48,7 @@ class JettyVirtualThreadsWebServerFactoryCustomizerTests {
 			assertThat(threadPool).isInstanceOf(VirtualThreadPool.class);
 			VirtualThreadPool virtualThreadPool = (VirtualThreadPool) threadPool;
 			assertThat(virtualThreadPool.getName()).isEqualTo("jetty-");
-			assertThat(virtualThreadPool.getMaxThreads()).isEqualTo(100);
+			assertThat(virtualThreadPool.getMaxConcurrentTasks()).isEqualTo(100);
 		}));
 	}
 

platform/spring-boot-dependencies/build.gradle

@@ -1083,7 +1083,7 @@ bom {
 			]
 		}
 	}
-	library("Jetty", "12.1.5") {
+	library("Jetty", "12.1.6") {
 		prohibit {
 			contains ".alpha"
 			because "we don't want alpha dependencies"