//
            // idea:idea
            //
            String prefix = tok[0];

            if (numTokens == 2) {
                goal = tok[1];
            } else {
                // goal was missing - pass through to MojoNotFoundException
                goal = "";
            }

            // This is the case where someone has executed a single goal from the command line
            // of the form:

            if (id == null || id.isEmpty()) {
                throw new InvalidRepositoryException("Repository identifier missing", "");
            }

            String url = repo.getUrl();

            if (url == null || url.isEmpty()) {
                throw new InvalidRepositoryException("URL missing for repository " + id, id);
            }

                PrintStream ps = new PrintStream(os);
                ps.println("Unable to load the mojo '" + mojoDescriptor.getGoal() + "' in the plugin '"
                        + pluginDescriptor.getId() + "'. A required class is missing: "
                        + cause.getMessage());
                pluginRealm.display(ps);

                throw new PluginContainerException(mojoDescriptor, pluginRealm, os.toString(), cause);

import org.apache.maven.artifact.versioning.OverConstrainedVersionException;

/**
 * Specific problems during resolution that we want to account for:
 * <ul>
 *   <li>missing metadata</li>
 *   <li>version range violations</li>
 *   <li>version circular dependencies</li>
 *   <li>missing artifacts</li>
 *   <li>network/transfer errors</li>
 *   <li>file system errors: permissions</li>
 * </ul>
 *

    }

    private void printErrors(ArtifactResolutionResult result) {
        if (result.hasMissingArtifacts()) {
            for (Artifact artifact : result.getMissingArtifacts()) {
                System.err.println("Missing: " + artifact);
            }
        }

        if (result.hasExceptions()) {
            for (Exception e : result.getExceptions()) {
                e.printStackTrace();
            }
        }

     * @param foreignImports The packages/types to import from foreign realms, may be {@code null}.
     * @param artifacts The artifacts to add to the realm, may be {@code null}. Unresolved artifacts (i.e. with a
     *            missing file) will automatically be excluded from the realm.
     * @return The created class realm, never {@code null}.
     */
    private ClassRealm createRealm(
            String baseRealmId,
            RealmType type,

                        .exists(settingsFile.getExists())
                        .missing(settingsFile.getMissing())
                        .location("exists", toLocation(settingsFile.getLocation("exists")))
                        .location("missing", toLocation(settingsFile.getLocation("missing")))
                        .build());
            }

                scenario("Selected optional project")
                        .activeOptionalProjects(MODULE_B)
                        .expectResult(MODULE_B),
                scenario("Selected missing optional project")
                        .activeOptionalProjects("non-existing-module")
                        .expectResult(
                                PARENT_MODULE,
                                MODULE_C,

            ByteArrayOutputStream os = new ByteArrayOutputStream(1024);
            PrintStream ps = new PrintStream(os);
            ps.println(
                    "A required class was missing while executing " + mojoDescriptor.getId() + ": " + e.getMessage());
            pluginRealm.display(ps);
            Exception wrapper = new PluginContainerException(mojoDescriptor, pluginRealm, os.toString(), e);

  a result turning off certain services provided by m2 and providing a coherent
  way of predicting and reporting when network-related failures will take place.
  It means warning users that since the network is missing, certain features and
  operations will be unavailable, rather than simply waiting for those
  operations to fail, then trying to help users decipher the error messages they
  get as a result.