activation = new ProjectActivation();
        performProjectActivation(
                parser.parse(options, new String[] {"-pl", "test1,+test2,?test3,+?test4"}), activation);
        assertContainsExactlyInAnyOrder(activation.getRequiredActiveProjectSelectors(), "test1", "test2");
        assertContainsExactlyInAnyOrder(activation.getOptionalActiveProjectSelectors(), "test3", "test4");

        activation = new ProjectActivation();

                result.getWarnings().get(0));

        assertEquals(
                "'profiles.profile[missing-project-version].activation.file.missing' "
                        + "Failed to interpolate profile activation property ${project.version}/test.txt: "
                        + "${project.version} expressions are not supported during profile activation.",
                result.getWarnings().get(1));

          <description>The ID of this build profile, for activation
            purposes.</description>
        </field>
        <field>
          <name>activation</name>
          <version>1.0.0</version>
          <description><![CDATA[The conditional logic which will automatically
            trigger the inclusion of this profile.]]></description>
          <association>
            <type>Activation</type>
          </association>
        </field>

     |
     | This profile example uses the JDK version to trigger activation, and provides a JDK-specific repo.
    <profile>
      <id>jdk-1.4</id>

      <activation>
        <jdk>1.4</jdk>
      </activation>

      <repositories>
        <repository>
          <id>jdk14</id>
          <name>Repository for JDK 1.4 builds</name>

                }
                // Activation
                visit(profile.getActivation());
                // Build
                visit(profile.getBuild());
            }
        }

        private void visit(Activation activation) {
            if (activation != null) {
                String org, val;
                // Jdk
                org = activation.getJdk();
                val = interpolate(org);

import org.apache.maven.model.profile.activation.FileProfileActivator;
import org.apache.maven.model.profile.activation.JdkVersionProfileActivator;
import org.apache.maven.model.profile.activation.OperatingSystemProfileActivator;
import org.apache.maven.model.profile.activation.ProfileActivator;
import org.apache.maven.model.profile.activation.PropertyProfileActivator;

 that manages the steps sequence.

 The sequence is divided into 2 phases:

 * phase 1

   ** profile activation: see {{{./apidocs/org/apache/maven/model/profile/activation/package-summary.html}available activators}}.
   Notice that model interpolation hasn't happened yet, then interpolation for file-based activation is limited to
   <<<$\{basedir}>>> (since Maven 3), <<<$\{rootDirectory}>>> (since Maven 4), system properties and user properties

    /**
     * Return the requested activation(s) of project(s) in this execution.
     * @return requested (de-)activation(s) of project(s) in this execution. Never {@code null}.
     */
    ProjectActivation getProjectActivation();

    /**
     * Return the requested activation(s) of profile(s) in this execution.
     * @return requested (de-)activation(s) of profile(s) in this execution. Never {@code null}.
     */

     * from the runtime environment like {@link System#getProperties()} and environment variables.
     *
     * @return The system properties, never {@code null}.
     */
    Properties getSystemProperties();

    /**
     * Sets the system properties to use for interpolation and profile activation. The system properties are collected

        </executions>
      </plugin>
    </plugins>
  </build>

  <profiles>
    <profile>
      <id>create-distribution-in-dir</id>
      <activation>
        <property>
          <name>distributionTargetDir</name>
        </property>
      </activation>
      <build>
        <plugins>
          <plugin>
            <groupId>org.apache.maven.plugins</groupId>