Resolves #951: DefaultArtifactVersion::getVersion can be null

versions-common/src/main/java/org/codehaus/mojo/versions/api/ArtifactVersions.java

@@ -75,6 +75,9 @@ public ArtifactVersions(Artifact artifact, List<ArtifactVersion> versions, Versi
         this.versionComparator = versionComparator;
         this.versions = new TreeSet<>(versionComparator);
         this.versions.addAll(versions);
+        // DefaultArtifact objects are often built from raw model, without a version set
+        // (where the actual version is taken from parent or dependency/plugin management)
+        // this probably isn't the case in an actual Maven execution
         if (artifact.getVersion() != null) {
             setCurrentVersion(artifact.getVersion());
         }
@@ -119,8 +122,12 @@ public boolean equals(Object o) {
 
         ArtifactVersions that = (ArtifactVersions) o;
 
+        // can't just use Artifact::equals() since e.g. we can have an empty version here
         return new EqualsBuilder()
-                .append(getArtifact(), that.getArtifact())
+                .append(getArtifact().getGroupId(), that.getGroupId())
+                .append(getArtifact().getArtifactId(), that.getArtifact().getArtifactId())
+                .append(getArtifact().getVersion(), that.getArtifact().getVersion())
+                .append(getArtifact().getScope(), that.getArtifact().getScope())
                 .append(getVersions(true), that.getVersions(true))
                 .append(getVersionComparator(), that.getVersionComparator())
                 .isEquals();

versions-maven-plugin/src/it/it-dependency-updates-report-issue-951/invoker.properties

@@ -0,0 +1 @@
+invoker.goals = ${project.groupId}:${project.artifactId}:${project.version}:dependency-updates-report

versions-maven-plugin/src/it/it-dependency-updates-report-issue-951/pom.xml

@@ -0,0 +1,26 @@
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+  <modelVersion>4.0.0</modelVersion>
+  <groupId>localhost</groupId>
+  <artifactId>dummy-artifact</artifactId>
+  <version>1.0.0-SNAPSHOT</version>
+
+  <dependencyManagement>
+    <dependencies>
+      <dependency>
+        <groupId>localhost</groupId>
+        <artifactId>dummy-api</artifactId>
+        <version>[1.0,2.3]</version>
+        <scope>test</scope>
+      </dependency>
+    </dependencies>
+  </dependencyManagement>
+  <dependencies>
+    <dependency>
+      <groupId>localhost</groupId>
+      <artifactId>dummy-api</artifactId>
+      <scope>compile</scope>
+    </dependency>
+  </dependencies>
+
+</project>