Code review comment: I'll need to check whether it's safe to assume the file is always available and exists.

Code under review:
public void execute() throws MojoExecutionException {

        if (project.getPackaging().equals("pom")) {
            getLog().info("Type of the artifact is POM, skipping build goal");
            return;
        }
        if (skip) {
            getLog().info("Skipping Quarkus build");
            return;
        }

        boolean clear = false;
        try {

            final Properties projectProperties = project.getProperties();
            final Properties realProperties = new Properties();
            for (String name : projectProperties.stringPropertyNames()) {
                if (name.startsWith("quarkus.")) {
                    realProperties.setProperty(name, projectProperties.getProperty(name));
                }
            }
            if (uberJar && System.getProperty(QUARKUS_PACKAGE_UBER_JAR) == null) {
                System.setProperty(QUARKUS_PACKAGE_UBER_JAR, "true");
                clear = true;
            }
            realProperties.putIfAbsent("quarkus.application.name", project.getArtifactId());
            realProperties.putIfAbsent("quarkus.application.version", project.getVersion());

            MavenArtifactResolver resolver = MavenArtifactResolver.builder()
                    .setRepositorySystem(repoSystem)
                    .setRepositorySystemSession(repoSession)
                    .setRemoteRepositories(repos)
                    .build();

            final Artifact projectArtifact = project.getArtifact();
            final AppArtifact appArtifact = new AppArtifact(projectArtifact.getGroupId(), projectArtifact.getArtifactId(),
                    projectArtifact.getClassifier(), projectArtifact.getArtifactHandler().getExtension(),
                    projectArtifact.getVersion());
            appArtifact.setPaths(PathsCollection.of(projectArtifact.getFile().toPath()));

            CuratedApplication curatedApplication = QuarkusBootstrap.builder()
                    .setAppArtifact(appArtifact)
                    .setMavenArtifactResolver(resolver)
                    .setBaseClassLoader(BuildMojo.class.getClassLoader())
                    .setBuildSystemProperties(realProperties)
                    .setLocalProjectDiscovery(false)
                    .setBaseName(finalName)
                    .setTargetDirectory(buildDir.toPath())
                    .build().bootstrap();

            AugmentAction action = curatedApplication.createAugmentor();
            AugmentResult result = action.createProductionApplication();

            Artifact original = project.getArtifact();
            if (result.getJar() != null) {
                if (result.getJar().isUberJar() && result.getJar().getOriginalArtifact() != null) {
                    final Path standardJar = curatedApplication.getAppModel().getAppArtifact().getPaths().getSinglePath();
                    if (Files.exists(standardJar)) {
                        try {
                            Files.deleteIfExists(result.getJar().getOriginalArtifact());
                            Files.move(standardJar, result.getJar().getOriginalArtifact());
                        } catch (IOException e) {
                            throw new UncheckedIOException(e);
                        }
                        original.setFile(result.getJar().getOriginalArtifact().toFile());
                    }
                }
                if (result.getJar().isUberJar()) {
                    projectHelper.attachArtifact(project, result.getJar().getPath().toFile(), "runner");
                }
            }

        } catch (Exception e) {
            throw new MojoExecutionException("Failed to build quarkus application", e);
        } finally {
            if (clear) {
                System.clearProperty(QUARKUS_PACKAGE_UBER_JAR);
            }
        }
    }

Line commented on: appArtifact.setPaths(PathsCollection.of(projectArtifact.getFile().toPath()));

Revised code:
public void execute() throws MojoExecutionException {

        if (project.getPackaging().equals("pom")) {
            getLog().info("Type of the artifact is POM, skipping build goal");
            return;
        }
        if (skip) {
            getLog().info("Skipping Quarkus build");
            return;
        }

        boolean clear = false;
        try {

            final Properties projectProperties = project.getProperties();
            final Properties realProperties = new Properties();
            for (String name : projectProperties.stringPropertyNames()) {
                if (name.startsWith("quarkus.")) {
                    realProperties.setProperty(name, projectProperties.getProperty(name));
                }
            }
            if (uberJar && System.getProperty(QUARKUS_PACKAGE_UBER_JAR) == null) {
                System.setProperty(QUARKUS_PACKAGE_UBER_JAR, "true");
                clear = true;
            }
            realProperties.putIfAbsent("quarkus.application.name", project.getArtifactId());
            realProperties.putIfAbsent("quarkus.application.version", project.getVersion());

            MavenArtifactResolver resolver = MavenArtifactResolver.builder()
                    .setRepositorySystem(repoSystem)
                    .setRepositorySystemSession(repoSession)
                    .setRemoteRepositories(repos)
                    .build();

            final Artifact projectArtifact = project.getArtifact();
            final AppArtifact appArtifact = new AppArtifact(projectArtifact.getGroupId(), projectArtifact.getArtifactId(),
                    projectArtifact.getClassifier(), projectArtifact.getArtifactHandler().getExtension(),
                    projectArtifact.getVersion());
            appArtifact.setPaths(PathsCollection.of(projectArtifact.getFile().toPath()));

            CuratedApplication curatedApplication = QuarkusBootstrap.builder()
                    .setAppArtifact(appArtifact)
                    .setMavenArtifactResolver(resolver)
                    .setBaseClassLoader(BuildMojo.class.getClassLoader())
                    .setBuildSystemProperties(realProperties)
                    .setLocalProjectDiscovery(false)
                    .setBaseName(finalName)
                    .setTargetDirectory(buildDir.toPath())
                    .build().bootstrap();

            AugmentAction action = curatedApplication.createAugmentor();
            AugmentResult result = action.createProductionApplication();

            Artifact original = project.getArtifact();
            if (result.getJar() != null) {
                if (result.getJar().isUberJar() && result.getJar().getOriginalArtifact() != null) {
                    final Path standardJar = curatedApplication.getAppModel().getAppArtifact().getPaths().getSinglePath();
                    if (Files.exists(standardJar)) {
                        try {
                            Files.deleteIfExists(result.getJar().getOriginalArtifact());
                            Files.move(standardJar, result.getJar().getOriginalArtifact());
                        } catch (IOException e) {
                            throw new UncheckedIOException(e);
                        }
                        original.setFile(result.getJar().getOriginalArtifact().toFile());
                    }
                }
                if (result.getJar().isUberJar()) {
                    projectHelper.attachArtifact(project, result.getJar().getPath().toFile(), "runner");
                }
            }

        } catch (Exception e) {
            throw new MojoExecutionException("Failed to build quarkus application", e);
        } finally {
            if (clear) {
                System.clearProperty(QUARKUS_PACKAGE_UBER_JAR);
            }
        }
    }