- artifact metadata missing
- extension metadata missing
- extension artifact missing
- artifact metadata retrieval problem
- version range violation
- circular dependency
- artifact missing
- artifact retrieval exception
- md5 checksum doesn't match for local artifact, need to redownload this
- POM doesn't exist for a goal that requires one
- parent POM missing (in both the repository + relative path)

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

                    missingDescriptor(session, trace, a, (Exception) e.getCause());
                    if ((getPolicy(session, a, request) & ArtifactDescriptorPolicy.IGNORE_MISSING) != 0) {
                        return null;
                    }
                }
                result.addException(e);
                throw new ArtifactDescriptorException(result);
            }

        assertThat(
                e.getResults(),
                contains(projectBuildingResultWithProblemMessage(
                        "'dependencies.dependency.version' for org.apache.maven.its:a:jar is missing")));
        assertThat(e.getResults(), contains(projectBuildingResultWithLocation(5, 9)));
    }

    @Test
    void testResolveDependencies() throws Exception {

    @Inject
    private ArtifactRepositoryFactory artifactRepositoryFactory;

    @Test
    void testUnnecessaryRepositoryLookup() throws Exception {
        Artifact artifact = createTestPomArtifact("target/test-data/get-missing-pom");

        List<ArtifactRepository> repos = new ArrayList<>();
        repos.add(artifactRepositoryFactory.createArtifactRepository(
                "repo1", "string://url1", new ArtifactRepositoryLayoutStub(), null, null));

            return false;
        }

        if (!string.isEmpty()) {
            return true;
        }

        addViolation(problems, BuilderProblem.Severity.ERROR, fieldName, sourceHint, "is missing");

        return false;
    }

    /**
     * Asserts:
     * <p/>
     * <ul>
     * <li><code>string != null</code>
     * </ul>
     */
    private static boolean validateNotNull(

                request.getLocalRepository(),
                request.getRemoteRepositories());

        if (cached != null
                // if the POM has no file, we cached a missing artifact, only return the cached data if no update forced
                && (!request.isForceUpdate() || hasFile(cached.getPomArtifact()))) {
            return cached;
        }

        List<Dependency> dependencies;

                        // 1 extra '/' to remove
                        url.setLength(url.length() - 1);
                    }
                } else if (!initialUrlEndsWithSlash) {
                    // add missing '/' between url and path
                    url.append('/');
                }

                url.append(path);

                // ensure resulting url ends with slash if initial url was

            selectedProjects.addAll(
                    projectSelector.getOptionalProjectsBySelectors(request, allSortedProjects, optionalSelectors));

            // it can be empty when an optional project is missing from the reactor, fallback to returning all projects
            if (!selectedProjects.isEmpty()) {
                result = new ArrayList<>(selectedProjects);

        This is the file specification used to activate a profile. The missing value will be a the location
        of a file that needs to exist, and if it doesn't the profile must run.  On the other hand exists will test
        for the existence of the file and if it is there will run the profile.
      ]]></description>
      <fields>
        <field>
          <name>missing</name>
          <version>1.0.0</version>