SpringBoot Usage tomcat-embed-core and servlet-api: duplicate classes

I have a Spring Boot web project. One of libs has transitive dependency to jakarta.servlet:jakarta.servlet-api When we have org.apache.tomcat.embed:tomcat-embed-core:jar:9.0.43:compile and jakarta.servlet:jakarta.servlet-api:jar:4.0.4:compile in class path maven-enforcer-plugin fails

[WARNING] Rule 0: org.apache.maven.plugins.enforcer.BanDuplicateClasses failed with message: Duplicate classes found:

Found in: org.apache.tomcat.embed:tomcat-embed-core:jar:9.0.43:compile jakarta.servlet:jakarta.servlet-api:jar:4.0.4:compile Duplicate classes: javax/servlet/http/Cookie.class javax/servlet/ServletContext.class javax/servlet/Registration.class ...

Here is an example to reproduce use mvn verify

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.4.3</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.example</groupId>
    <artifactId>demo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>demo</name>
    <description>Demo project for Spring Boot</description>
    <properties>
        <java.version>11</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>jakarta.servlet</groupId>
            <artifactId>jakarta.servlet-api</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-enforcer-plugin</artifactId>
                <version>3.0.0-M3</version>
                <executions>
                    <execution>
                        <id>default-cli</id>
                        <goals>
                            <goal>enforce</goal>
                        </goals>
                        <configuration>
                            <rules>
                                <requireUpperBoundDeps>
                                    <excludes>
                                        <exclude>org.scala-lang:scala-library</exclude>
                                    </excludes>
                                </requireUpperBoundDeps>
                                <requireJavaVersion>
                                    <version>${java.version}</version>
                                </requireJavaVersion>
                                <requireMavenVersion>
                                    <version>3.6.0</version>
                                </requireMavenVersion>
                            </rules>
                        </configuration>
                    </execution>
                    <execution>
                        <id>enforce-ban-duplicate-classes</id>
                        <goals>
                            <goal>enforce</goal>
                        </goals>
                        <configuration>
                            <rules>
                                <banDuplicateClasses>
                                    <findAllDuplicates>true</findAllDuplicates>
                                </banDuplicateClasses>
                            </rules>
                            <fail>true</fail>
                        </configuration>
                    </execution>
                </executions>
                <dependencies>
                    <dependency>
                        <groupId>org.codehaus.mojo</groupId>
                        <artifactId>extra-enforcer-rules</artifactId>
                        <version>1.3</version>
                    </dependency>
                </dependencies>
            </plugin>

        </plugins>
    </build>

</project>

Is it possible to resolve it somehow? We can exclude jakarta.servlet:jakarta.servlet-api but it can leads to runtime errors because duplicate classes not equals.

Comment From: wilkinsona

You should exclude jakarta.servlet:jakarta.servlet-api from your dependencies as tomcat-embed-core contains every class in the Servlet API. If you have any further questions, please follow up on Stack Overflow or Gitter. As mentioned in the guidelines for contributing, we prefer to use GitHub issues only for bugs and enhancements.