plugin = (Plugin) data;
            }
            trace = trace.getParent();
        }

        Path trackingDir;
        boolean missing = event.getFile() == null;
        if (missing) {
            // missing artifact - let's track the path anyway
            File dir = event.getSession().getLocalRepository().getBasedir();
            dir = new File(

            protected ActivationFile.Builder transformActivationFile_Missing(
                    Supplier<? extends ActivationFile.Builder> creator,
                    ActivationFile.Builder builder,
                    ActivationFile target) {
                String path = target.getMissing();
                String xformed = transformPath(path, target, "missing");

            //
            // 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:

        }
    }

    @Override
    public void artifactDescriptorMissing(RepositoryEvent event) {
        logger.warn("The POM for {} is missing, no dependency information available", event.getArtifact());
    }

        // execute
        ToolchainPrivate[] toolchains = toolchainManager.getToolchainsForType("unknown", session);

        // verify
        verify(logger).error("Missing toolchain factory for type: unknown. Possibly caused by misconfigured project.");
        assertEquals(0, toolchains.length);
    }

    @Test
    void testToolchainsForConfiguredType() throws Exception {

        List<Toolchain> toolchains = toolchainManager.getToolchains(session, "unknown", null);

        assertEquals(0, toolchains.size());
        verify(logger).error("Missing toolchain factory for type: unknown. Possibly caused by misconfigured project.");
    }

    @Test
    void testModelAndFactory() {
        MavenSession session = mock(MavenSession.class);

            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);

        assertThrows(
                ProjectBuildingException.class,
                () -> buildPom("artifact-id-inheritance/child"),
                "Missing artifactId did not cause validation error");
    }

    private void assertPathSuffixEquals(String expected, Object actual) {
        String a = actual.toString();

    /**
     * @param originatingArtifact the artifact that was being resolved
     * @param missingArtifacts    artifacts that could not be resolved
     * @param remoteRepositories  remote repositories where the missing artifacts were not found
     * @deprecated use {@link #MultipleArtifactsNotFoundException(Artifact, List, List, List)}
     */
    @Deprecated
    public MultipleArtifactsNotFoundException(