Apache Maven get server password by executing external command

AWS CodeArtifact, for example, authenticates with a token valid for 12 hours. A typical setup of maven with CodeArtifact is:

  <servers>
    <server>
      <id>my-domain--my-repo</id>
      <username>aws</username>
      <password>${env.CODEARTIFACT_AUTH_TOKEN}</password>
    </server>
  </servers>

in settings.xml and executing

export CODEARTIFACT_AUTH_TOKEN=$(aws codeartifact get-authorization-token --domain my-domain --domain-owner 123456789012 --query authorizationToken --output text)

in terminal every 12 hours before invoking mvn.

I thought I could have:

  <servers>
    <server>
      <id>swifttech--main</id>
      <username>aws</username>
      <password>${codeartifact.auth.token}</password>
    </server>
  </servers>

in settings.xml and then have a

  <plugin>
    <groupId>org.codehaus.gmaven</groupId>
    <artifactId>gmaven-plugin</artifactId>
    <version>1.5</version>
    <executions>
      <execution>
        <phase>validate</phase>
        <goals>
          <goal>execute</goal>
        </goals>
        <configuration>
          <providerSelection>2.0</providerSelection>
          <properties>
            <script>aws codeartifact get-authorization-token --domain my-domain --domain-owner 123456789012 --query authorizationToken --output text</script>
          </properties>
          <source>
            def command = project.properties.script
            def process = command.execute()
            process.waitFor()

            def token = process.in.text.trim()

            project.properties.setProperty('codeartifact.auth.token', token)
          </source>
        </configuration>
      </execution>
    </executions>
  </plugin>

section in pom.xml to automate CodeArtifact token retrieval.

Except it didn't work. I wonder if the idea I have is valid altogether and what didn't work is just implementation flaw. Or is it just not possible to have this kind of automation with maven.