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);

        IOException ioEx = new IOException("Unable to establish loopback connection", connEx);
        MojoExecutionException mojoEx =
                new MojoExecutionException("Error executing Jetty: Unable to establish loopback connection", ioEx);

        ExceptionHandler exceptionHandler = new DefaultExceptionHandler();
        ExceptionSummary exceptionSummary = exceptionHandler.handleException(mojoEx);

         * the way 2.x works. When we're in strict mode, the removal of duplicates just saves other merging steps from
         * aftereffects and bogus error messages.
         */
        List<Dependency> dependencies = model.getDependencies();
        Map<String, Dependency> normalized = new LinkedHashMap<>(dependencies.size() * 2);

        }

        String version = context.getSystemProperties().get("java.version");

        if (version == null || version.isEmpty()) {
            problems.add(
                    BuilderProblem.Severity.ERROR,
                    ModelProblem.Version.BASE,
                    "Failed to determine Java version for profile " + profile.getId(),
                    activation.getLocation("jdk"));
            return false;
        }

    public InvalidPluginDescriptorException(String message, List<String> errors) {
        super(toMessage(message, errors));
    }

    private static String toMessage(String message, List<String> errors) {
        StringBuilder buffer = new StringBuilder(256);
        buffer.append(message);
        for (String error : errors) {
            buffer.append(", ").append(error);
        }
        return buffer.toString();
    }

                    new ProjectExecutionEvent(session, currentProject, t));

            // rethrow original errors and runtime exceptions
            if (t instanceof RuntimeException) {
                throw (RuntimeException) t;
            }
            if (t instanceof Error) {
                throw (Error) t;
            }
        } finally {
            session.setCurrentProject(null);

@Experimental
public interface ArtifactResolver extends Service {

    /**
     * @param request {@link ArtifactResolverRequest}
     * @return {@link ArtifactResolverResult}
     * @throws ArtifactResolverException in case of an error
     * @throws IllegalArgumentException in case of parameter {@code buildingRequest} is {@code null} or
     *             parameter {@code mavenArtifact} is {@code null} or invalid
     */

     * @param artifact the artifact definition
     * @param deploymentRepository the repository to deploy to
     * @param localRepository the local repository to install into
     * @throws ArtifactDeploymentException if an error occurred deploying the artifact
     * @deprecated to be removed before 2.0 after the install/deploy plugins use the alternate
     *             method
     */
    @Deprecated
    void deploy(
            String basedir,

                a = factory.createBuildArtifact("org.apache.maven", "h", "1.0", "jar");
                dependencies.add(a);
            } catch (Exception e) {
                throw new ArtifactMetadataRetrievalException("Error retrieving metadata", e, a);
            }
        }

        if ("i".equals(artifact.getArtifactId())) {
            Artifact a = null;
            try {

     * @param message The message describing the problem, may be {@code null}.
     * @param severity The severity level of the problem, may be {@code null} to default to
     *            {@link org.apache.maven.building.Problem.Severity#ERROR}.
     * @param source A hint about the source of the problem like a file path, may be {@code null}.
     * @param lineNumber The one-based index of the line containing the problem or {@code -1} if unknown.