Maven 4 ignores <default-phases> from components.xml for standard lifecycle phases

[mariuszs]

Description

When a Maven plugin registers a custom lifecycle via META-INF/plexus/components.xml with <default-phases> binding goals to standard lifecycle phases (e.g. process-sources), Maven 4 loads the custom lifecycle but does not apply the default phase bindings. The same plugin works correctly on Maven 3.

This is different from MNG-8299 which tests custom phase names invoked directly (mvn phase3). This issue is about binding plugin goals to standard default lifecycle phases via <extensions>true</extensions>.

Steps to reproduce

Minimal reproducer: https://github.com/mariuszs/extension-maven-plugin

1. Clone the repo
2. mvn install -DskipTests
3. Run the extension-it test project:

cd src/it/extension-it
# substitute template variables
sed 's/@project.groupId@/com.skillpanel/;s/@project.artifactId@/extension-maven-plugin/;s/@project.version@/1.0-SNAPSHOT/' pom.xml > /tmp/test-pom.xml
mvn compile -f /tmp/test-pom.xml

4. Check for target/touch.txt — it should exist but doesn't on Maven 4.

The plugin's components.xml:

<component-set>
  <components>
    <component>
      <role>org.apache.maven.lifecycle.Lifecycle</role>
      <implementation>org.apache.maven.lifecycle.Lifecycle</implementation>
      <role-hint>extension-maven-plugin</role-hint>
      <configuration>
        <id>extension-maven-plugin</id>
        <phases>
          <phase>extension-not-used-phase</phase>
        </phases>
        <default-phases>
          <process-sources>
            com.skillpanel:extension-maven-plugin:touch
          </process-sources>
        </default-phases>
      </configuration>
    </component>
  </components>
</component-set>

The consuming project POM (no <executions> needed — extensions handle binding):

<plugin>
  <groupId>com.skillpanel</groupId>
  <artifactId>extension-maven-plugin</artifactId>
  <version>1.0-SNAPSHOT</version>
  <extensions>true</extensions>
</plugin>

Expected behavior

On Maven 3.9.x: the touch goal is automatically bound to process-sources phase via <default-phases>. Running mvn compile produces target/touch.txt.

[INFO] --- extension:1.0-SNAPSHOT:touch (default-touch) @ extension-it ---

Actual behavior

On Maven 4.0.0-rc-5: the custom lifecycle is loaded but <default-phases> bindings are not applied. Debug log shows:

[DEBUG] Lifecycle extension-maven-plugin -> [extension-not-used-phase]

Only the dummy phase is visible — no goal bindings to process-sources. The touch goal never executes, target/touch.txt is not created.

Environment

• Maven 4.0.0-rc-5
• Maven 3.9.13 (works correctly)
• Java 25 (also reproduced on Java 17)
• Linux

[mariuszs]

Root cause analysis

The issue is in DefaultLifecycleRegistry.LifecycleWrapperProvider.wrap() (source).

The conversion path

1. Plexus creates legacy Lifecycle with phases=["extension-not-used-phase"] and defaultPhases={"process-sources": "com.skillpanel:extension-maven-plugin:touch"}

2. LifecycleWrapperProvider.wrap() converts this to the new org.apache.maven.api.Lifecycle interface, but only creates Phase objects for names from getPhases() — i.e. only extension-not-used-phase

3. Each Phase's plugins() method does consult lifecycle.getDefaultLifecyclePhases(), but it looks up by its own name. Since no Phase object exists for process-sources, that binding is silently lost.

4. DefaultLifecycles.lookupLifecycles() then wraps the new API Lifecycle back into a legacy Lifecycle. It extracts defaultPhases from the new API phases — but those have no plugins (lost in step 2). Result: defaultPhases is empty.

5. DefaultLifecyclePluginAnalyzer.getPluginsBoundByDefaultToAllLifecycles() correctly reads getDefaultLifecyclePhases(), but receives an empty map.

The fundamental issue

In Maven 3, <default-phases> was a mechanism to bind plugin goals to phases of other lifecycles (the standard default lifecycle), not just phases of the custom lifecycle itself. The new Maven 4 Lifecycle API (Phase.plugins()) assumes bindings are scoped to the lifecycle's own phases. The bridge code in wrap() cannot represent these cross-lifecycle bindings.

Debug log confirms the lifecycle is loaded but without bindings:

[DEBUG] Lifecycle extension-maven-plugin -> [extension-not-used-phase]

The toString() on the new API Lifecycle only shows phases from getPhases(), confirming process-sources binding was dropped during conversion.