They are replaced in Maven 4 with Maven 4 API Core's {{{../api/maven-api-core/apidocs/org/apache/maven/api/Type.html}Dependency Types}},
  with default values defined in {{{../maven-resolver-provider/apidocs/org/apache/maven/repository/internal/type/DefaultTypeProvider.html}DefaultTypeProvider}}.

  For compatibility, legacy Maven 3 artifact handlers are still provided:

 themselves:

+-----+
<plugins>
  <plugin>
   <id>xdoc</id>
   <version>1.0</version>
   <parameters>
     <parameter>
       <name>theme</name>
       <value>classic</value>
     </parameter>
   </parameters>
  </plugin>
</plugins>
+-----+

Unified source directory

 Unified source directory structure that is analogous to the repository