if (pomFile.canRead()) {
                    return length != pomFile.length() || timestamp != pomFile.lastModified();
                } else {
                    // if the POM didn't exist, retry if any repo is configured to always update
                    boolean snapshot = pomArtifact.isSnapshot();
                    for (ArtifactRepository repository : remoteRepositories) {
                        ArtifactRepositoryPolicy policy =

        if (!localFile.exists()) {
            if (request.getRemoteRepositories().isEmpty()) {
                throw new IOException(localFile + " does not exist and no remote repositories are configured");
            }

            ArtifactRepository remoteRepo = request.getRemoteRepositories().get(0);

            File remoteFile = new File(remoteRepo.getBasedir(), remoteRepo.pathOf(artifact));

    @Nonnull
    List<RemoteRepository> getRemoteRepositories();

    @Nonnull
    SessionData getData();

    /**
     * Returns 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

         * unintentionally use such a magic expression for an ordinary property. So here we check whether we
         * ended up with a magic value that is not compatible with the type of the configured mojo parameter (a string
         * could still be converted by the configurator so we leave those alone). If so, back off to evaluating the
         * expression from properties only.
         */

    public List<String> getGoals() {
        return request.getGoals();
    }

    /**
     * Gets the user properties to use for interpolation and profile activation. The user properties have been
     * configured directly by the user on his discretion, e.g. via the {@code -Dkey=value} parameter on the command
     * line.
     *
     * @return The user properties, never {@code null}.
     */

  mode.

** Maven-Core

  We'll examine the different parts of maven-core on a case-by-case
  basis, below:

*** DefaultLifecycleExecutor

  When binding goals to the project's configured lifecycle, each mojo
  descriptor should declare whether it requires online/offline status.
  This value should be a java.lang.Boolean, so it can implement 3VL
  (three value logic: yes, no, don't-care). The requiresOnline

          <name>editable</name>
          <version>1.0.0+</version>
          <type>boolean</type>
          <defaultValue>true</defaultValue>
          <description>
            Specifies that this parameter can be configured directly by the user (as in the case of POM-specified
            configuration). This is useful when you want to force the user to use common POM elements rather than

         * unintentionally use such a magic expression for an ordinary property. So here we check whether we
         * ended up with a magic value that is not compatible with the type of the configured mojo parameter (a string
         * could still be converted by the configurator so we leave those alone). If so, back off to evaluating the
         * expression from properties only.
         */

     */
    Properties getSystemProperties();

    /**
     * Sets the user properties to use for interpolation and profile activation. The user properties have been
     * configured directly by the user on his discretion, e.g. via the {@code -Dkey=value} parameter on the command
     * line.
     *
     * @param userProperties The user properties, may be {@code null}.

         * descriptor and a corresponding artifact file. The root artifact on the other hand is only used
         * as a label for the root node of the graph in case no root dependency was specified. As such, the configured
         * root artifact is ignored if {@link #root(DependencyCoordinate)} has been set.
         *
         * @param rootArtifact the root artifact for the dependency graph, may be {@code null}