title: Embedded Tomcat 10 does not listen on port in Spring Boot application
body: <p>I have a Spring Boot application which uses Tomcat. With version 9.0.36 it runs fine, and with 10.0.0-M7 fails. Part of pom.xml related to Tomcat is:</p>
  <pre><code>    &lt;/properties&gt;
              &lt;tomcat.version&gt;10.0.0-M7&lt;/tomcat.version&gt;
      &lt;/properties&gt;
  
      &lt;dependency&gt;
          &lt;groupId&gt;org.springframework.boot&lt;/groupId&gt;
          &lt;artifactId&gt;spring-boot-starter-web&lt;/artifactId&gt;
      &lt;/dependency&gt;
  </code></pre>
  <p>application.yml's section responsible for Tomcat:</p>
  <pre><code>server:
    port: 28088
    servlet:
      contextPath: /rest
    main:
      web-application-type: servlet
    tomcat:
      max-threads: 64
  </code></pre>
  <p>With Tomcat 9.0.36, everything is fine. From the log:</p>
  <pre><code>2020-07-20 16:56:10.596  INFO 8268 --- [           main] .s.d.r.c.RepositoryConfigurationDelegate : Bootstrapping Spring Data MongoDB repositories in DEFAULT mode.
  2020-07-20 16:56:10.637  INFO 8268 --- [           main] .s.d.r.c.RepositoryConfigurationDelegate : Finished Spring Data repository scanning in 35ms. Found 0 MongoDB repository interfaces.
  2020-07-20 16:56:11.493  INFO 8268 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat initialized with port(s): 28088 (http)
  2020-07-20 16:56:11.505  INFO 8268 --- [           main] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
  2020-07-20 16:56:11.506  INFO 8268 --- [           main] org.apache.catalina.core.StandardEngine  : Starting Servlet engine: [Apache Tomcat/9.0.36]
  2020-07-20 16:56:11.689  INFO 8268 --- [           main] o.a.c.c.C.[Tomcat].[localhost].[/rest]   : Initializing Spring embedded WebApplicationContext
  2020-07-20 16:56:11.689  INFO 8268 --- [           main] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 2278 ms
  2020-07-20 16:56:12.229  INFO 8268 --- [           main] org.mongodb.driver.cluster               : Cluster created with settings {hosts=[...:27017], mode=SINGLE, requiredClusterType=UNKNOWN, serverSelectionTimeout='30000 ms'}
  </code></pre>
  <p>But as soon as I replace 9.0.36 with 10.0.0-M7, it does not start Tomcat:</p>
  <pre><code>2020-07-20 16:59:24.184  INFO 20036 --- [           main] .s.d.r.c.RepositoryConfigurationDelegate : Bootstrapping Spring Data MongoDB repositories in DEFAULT mode.
  2020-07-20 16:59:24.242  INFO 20036 --- [           main] .s.d.r.c.RepositoryConfigurationDelegate : Finished Spring Data repository scanning in 51ms. Found 0 MongoDB repository interfaces.
  2020-07-20 16:59:25.298  INFO 20036 --- [           main] org.mongodb.driver.cluster               : Cluster created with settings {hosts=[...:27017], mode=SINGLE, requiredClusterType=UNKNOWN, serverSelectionTimeout='30000 ms'}
  </code></pre>
  <p>Anybody successfully used embedded Tomcat 10 with Spring Boot? I have upgraded to the latest Spring Boot 2.3.1-RELEASE to no avail.</p>