The following is the image we want to run the  legacy test (JUnit 4 in this case) inside the JUnit Plaform:

package io.github.bonigarcia;

import static org.junit.Assert.assertEquals;

import org.junit.Test;

public class LegacyJUnit4Test {

   @Test
   public void myFirstTest() {
      String message = "1+1 should be equal to 2";
      System.out.println(message);
      assertEquals(message, 2, 1 + 1);
   }

}

To that aim, in Maven, we first need to include the old JUnit 4 dependency in our pom.xml, as follows:

<dependencies>
   <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.12</version>
      <scope>test</scope>
   </dependency>
</dependencies>

Then, we need to include maven-surefire-plugin, using the following dependencies for the plugin: the Test Engine (junit-vintage-engine) and the Test Launcher (junit-platform-surefire-provider):

<build>
   <plugins>
      <plugin>
         <artifactId>maven-surefire-plugin</artifactId>
         <version>${maven-surefire-plugin.version}</version>
         <dependencies>
            <dependency>
               <groupId>org.junit.platform</groupId>
               <artifactId>junit-platform-surefire-provider</artifactId>
               <version>${junit.platform.version}</version>
            </dependency>
            <dependency>
                <groupId>org.junit.vintage</groupId>
                <artifactId>junit-vintage-engine</artifactId>
                <version>${junit.vintage.version}</version>
            </dependency>
         </dependencies>
      </plugin>
   </plugins>
</build>

The execution from the command line will also be using the command mvn test: