[MNG-8211] Fail the build if project effective version has expression (#1673)

As this is almost always source of confusion. If feature is used and there is no proper value set, fail the build, as users for sure does not plan to deploy artifacts with version `${revision}` (or any expression in project.version).

Still, to not be disruptive, the old behaviour can be achieved by setting `maven.build.allowExpressionInEffectiveProjectVersion`=true project property.

---

https://issues.apache.org/jira/browse/MNG-8211

Author: cstamas

maven-api-impl/src/main/java/org/apache/maven/internal/impl/model/DefaultModelValidator.java

@@ -78,6 +78,8 @@
 @Named
 @Singleton
 public class DefaultModelValidator implements ModelValidator {
+    public static final String BUILD_ALLOW_EXPRESSION_IN_EFFECTIVE_PROJECT_VERSION =
+            "maven.build.allowExpressionInEffectiveProjectVersion";
 
     public static final List<String> VALID_MODEL_VERSIONS =
             Collections.unmodifiableList(Arrays.asList("4.0.0", "4.1.0"));
@@ -699,6 +701,22 @@ public void validateEffectiveModel(Model m, ModelBuilderRequest request, ModelPr
             validateBannedCharacters(
                     EMPTY, "version", problems, errOn31, Version.V20, m.getVersion(), null, m, ILLEGAL_VERSION_CHARS);
             validate20ProperSnapshotVersion("version", problems, errOn31, Version.V20, m.getVersion(), null, m);
+            if (hasExpression(m.getVersion())) {
+                Severity versionExpressionSeverity = Severity.ERROR;
+                if (m.getProperties() != null
+                        && Boolean.parseBoolean(
+                                m.getProperties().get(BUILD_ALLOW_EXPRESSION_IN_EFFECTIVE_PROJECT_VERSION))) {
+                    versionExpressionSeverity = Severity.WARNING;
+                }
+                addViolation(
+                        problems,
+                        versionExpressionSeverity,
+                        Version.V20,
+                        "version",
+                        null,
+                        "must be a constant version but is '" + m.getVersion() + "'.",
+                        m);
+            }
 
             Build build = m.getBuild();
             if (build != null) {

maven-model-builder/src/main/java/org/apache/maven/model/validation/DefaultModelValidator.java

@@ -80,6 +80,8 @@
 @Named
 @Singleton
 public class DefaultModelValidator implements ModelValidator {
+    public static final String BUILD_ALLOW_EXPRESSION_IN_EFFECTIVE_PROJECT_VERSION =
+            "maven.build.allowExpressionInEffectiveProjectVersion";
 
     public static final List<String> VALID_MODEL_VERSIONS =
             Collections.unmodifiableList(Arrays.asList("4.0.0", "4.1.0"));
@@ -691,6 +693,22 @@ public void validateEffectiveModel(Model ma, ModelBuildingRequest request, Model
             validateBannedCharacters(
                     EMPTY, "version", problems, errOn31, Version.V20, m.getVersion(), null, m, ILLEGAL_VERSION_CHARS);
             validate20ProperSnapshotVersion("version", problems, errOn31, Version.V20, m.getVersion(), null, m);
+            if (hasExpression(m.getVersion())) {
+                Severity versionExpressionSeverity = Severity.ERROR;
+                if (m.getProperties() != null
+                        && Boolean.parseBoolean(
+                                m.getProperties().get(BUILD_ALLOW_EXPRESSION_IN_EFFECTIVE_PROJECT_VERSION))) {
+                    versionExpressionSeverity = Severity.WARNING;
+                }
+                addViolation(
+                        problems,
+                        versionExpressionSeverity,
+                        Version.V20,
+                        "version",
+                        null,
+                        "must be a constant version but is '" + m.getVersion() + "'.",
+                        m);
+            }
 
             Build build = m.getBuild();
             if (build != null) {