private boolean isPackagedArtifactUpToDate(MavenProject project, File packagedArtifactFile) {
        Path outputDirectory = Paths.get(project.getBuild().getOutputDirectory());
        if (!outputDirectory.toFile().exists()) {
            return true;
        }

        try (Stream<Path> outputFiles = Files.walk(outputDirectory)) {
            // Not using File#lastModified() to avoid a Linux JDK8 milliseconds precision bug: JDK-8177809.

                <configuration>
                  <finalName>./</finalName>
                  <appendAssemblyId>false</appendAssemblyId>
                  <attach>false</attach>
                  <outputDirectory>${distributionTargetDir}</outputDirectory>
                  <descriptors>
                    <descriptor>src/assembly/dir.xml</descriptor>
                  </descriptors>
                </configuration>
              </execution>

        assertProblemFree(collector);

        assertEquals("/path/to/home", out.getProperties().get("outputDirectory"));
    }

    @Test
    public void envarExpressionThatEvaluatesToNullReturnsTheLiteralString() throws Exception {

        Map<String, String> modelProperties = new HashMap<>();
        modelProperties.put("outputDirectory", "${env.DOES_NOT_EXIST}");

        translatedPrefixes.add("build.outputDirectory");
        translatedPrefixes.add("build.testOutputDirectory");
        translatedPrefixes.add("build.sourceDirectory");
        translatedPrefixes.add("build.testSourceDirectory");
        translatedPrefixes.add("build.scriptSourceDirectory");
        translatedPrefixes.add("reporting.outputDirectory");

        TRANSLATED_PATH_EXPRESSIONS = translatedPrefixes;
    }

        translatedPrefixes.add("build.outputDirectory");
        translatedPrefixes.add("build.testOutputDirectory");
        translatedPrefixes.add("build.sourceDirectory");
        translatedPrefixes.add("build.testSourceDirectory");
        translatedPrefixes.add("build.scriptSourceDirectory");
        translatedPrefixes.add("reporting.outputDirectory");

        TRANSLATED_PATH_EXPRESSIONS = translatedPrefixes;
    }