While the source code of example apps was fixed during javax->jakarta transition,  prebuilt artifact webapps/docs/appdev/sample/sample.war was not rebuilt and is still using old javax imports and fails during deploy attempts. 
Tested with Tomcat 9, 10 and 11.

$ javap Hello.class 
Compiled from "Hello.java"
public final class mypackage.Hello extends javax.servlet.http.HttpServlet {
  public mypackage.Hello();
  public void doGet(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse) throws java.io.IOException, javax.servlet.ServletException;
}

$ javap -v Hello.class 
Classfile /tmp/Hello.class
  Last modified Jul 30, 2007; size 1480 bytes
  SHA-256 checksum 566f7f35c006fbcd5a05b506d779fe7bf2d0d761b1062dcbdd2efe5be584a174
  Compiled from "Hello.java"
public final class mypackage.Hello extends javax.servlet.http.HttpServlet
  minor version: 0
  major version: 49
  flags: (0x0031) ACC_PUBLIC, ACC_FINAL, ACC_SUPER
  this_class: #23                         // mypackage/Hello
  super_class: #24                        // javax/servlet/http/HttpServlet
  interfaces: 0, fields: 0, methods: 2, attributes: 1
....