[MNG-8006] SPI to contribute to effective properties and more

api/maven-api-core/src/main/java/org/apache/maven/api/Project.java

@@ -20,6 +20,7 @@
 
 import java.nio.file.Path;
 import java.util.List;
+import java.util.Map;
 import java.util.Optional;
 
 import org.apache.maven.api.annotations.Experimental;
@@ -133,4 +134,10 @@ default String getId() {
 
     @Nonnull
     List<RemoteRepository> getRemotePluginRepositories();
+
+    /**
+     * Returns the effective project properties.
+     */
+    @Nonnull
+    Map<String, String> getProperties();
 }

api/maven-api-core/src/main/java/org/apache/maven/api/Session.java

@@ -28,6 +28,7 @@
 
 import org.apache.maven.api.annotations.Experimental;
 import org.apache.maven.api.annotations.Nonnull;
+import org.apache.maven.api.annotations.Nullable;
 import org.apache.maven.api.annotations.ThreadSafe;
 import org.apache.maven.api.model.Repository;
 import org.apache.maven.api.services.DependencyCoordinateFactory;
@@ -55,23 +56,31 @@ public interface Session {
     SessionData getData();
 
     /**
-     * Gets the user properties to use for interpolation. The user properties have been configured directly by the user,
-     * e.g. via the {@code -Dkey=value} parameter on the command line.
+     * Gets the immutable user properties to use for interpolation. The user properties have been configured directly
+     * by the user, e.g. via the {@code -Dkey=value} parameter on the command line.
      *
      * @return the user properties, never {@code null}
      */
     @Nonnull
     Map<String, String> getUserProperties();
 
     /**
-     * Gets the system properties to use for interpolation. The system properties are collected from the runtime
-     * environment such as {@link System#getProperties()} and environment variables.
+     * Gets the immutable system properties to use for interpolation. The system properties are collected from the
+     * runtime environment such as {@link System#getProperties()} and environment variables.
      *
      * @return the system properties, never {@code null}
      */
     @Nonnull
     Map<String, String> getSystemProperties();
 
+    /**
+     * Gets the effective properties to use for interpolation.
+     *
+     * @return the effective properties, never {@code null}
+     */
+    @Nonnull
+    Map<String, String> getEffectiveProperties(@Nullable Project project);
+
     /**
      * Returns the current maven version
      * @return the maven version, never {@code null}

api/maven-api-core/src/main/java/org/apache/maven/api/services/Properties.java

@@ -0,0 +1,43 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.maven.api.services;
+
+import java.util.Map;
+
+import org.apache.maven.api.*;
+import org.apache.maven.api.annotations.Experimental;
+import org.apache.maven.api.annotations.Nonnull;
+import org.apache.maven.api.annotations.Nullable;
+
+/**
+ * @since 4.0.0
+ */
+@Experimental
+public interface Properties extends Service {
+
+    /**
+     * Creates a {@link org.apache.maven.api.Project} from a POM file.
+     *
+     * @param project {@link Project} or {@code null}.
+     * @return the {@link Map} containing the effective properties.
+     * @throws IllegalArgumentException if an argument is {@code null} or invalid
+     */
+    @Nonnull
+    Map<String, String> effectiveProperties(@Nonnull Session session, @Nullable Project project);
+}

api/maven-api-spi/src/main/java/org/apache/maven/api/spi/session/EffectivePropertyContributor.java

@@ -0,0 +1,40 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.maven.api.spi.session;
+
+import java.util.Map;
+
+import org.apache.maven.api.Session;
+import org.apache.maven.api.annotations.Experimental;
+
+/**
+ * Component able to contribute to Maven session effective properties. This SPI component is invoked
+ * very early, while there is no session created yet.
+ */
+@Experimental
+public interface EffectivePropertyContributor {
+    /**
+     * Invoked just before session is created with a mutable map that carries collected effective properties so far.
+     * Values set here will override everything coming from {@link Session#getSystemProperties()} and
+     * {@link Session#getUserProperties()} and can be queried via {@link Session#getEffectiveProperties()}.
+     *
+     * @param effectiveProperties The mutable effective properties, never {@code null}.
+     */
+    void contribute(Map<String, Object> effectiveProperties);
+}

maven-core/src/main/java/org/apache/maven/DefaultMaven.java

@@ -59,8 +59,6 @@
 import org.apache.maven.execution.ProjectDependencyGraph;
 import org.apache.maven.graph.GraphBuilder;
 import org.apache.maven.graph.ProjectSelector;
-import org.apache.maven.internal.aether.DefaultRepositorySystemSessionFactory;
-import org.apache.maven.internal.aether.MavenChainedWorkspaceReader;
 import org.apache.maven.internal.impl.DefaultSessionFactory;
 import org.apache.maven.internal.impl.InternalSession;
 import org.apache.maven.lifecycle.LifecycleExecutionException;
@@ -71,6 +69,8 @@
 import org.apache.maven.model.superpom.SuperPomProvider;
 import org.apache.maven.plugin.LegacySupport;
 import org.apache.maven.project.MavenProject;
+import org.apache.maven.resolver.MavenChainedWorkspaceReader;
+import org.apache.maven.resolver.RepositorySystemSessionFactory;
 import org.apache.maven.session.scope.internal.SessionScope;
 import org.eclipse.aether.RepositorySystemSession;
 import org.eclipse.aether.RepositorySystemSession.CloseableSession;
@@ -99,7 +99,7 @@ public class DefaultMaven implements Maven {
 
     private final SessionScope sessionScope;
 
-    private final DefaultRepositorySystemSessionFactory repositorySessionFactory;
+    private final RepositorySystemSessionFactory repositorySessionFactory;
 
     private final GraphBuilder graphBuilder;
 
@@ -123,7 +123,7 @@ public DefaultMaven(
             ExecutionEventCatapult eventCatapult,
             LegacySupport legacySupport,
             SessionScope sessionScope,
-            DefaultRepositorySystemSessionFactory repositorySessionFactory,
+            RepositorySystemSessionFactory repositorySessionFactory,
             @Named(GraphBuilder.HINT) GraphBuilder graphBuilder,
             BuildResumptionAnalyzer buildResumptionAnalyzer,
             BuildResumptionDataRepository buildResumptionDataRepository,