[MNG-6964] Maven version sorting is internally inconsistent.

maven-artifact/src/main/java/org/apache/maven/artifact/versioning/ComparableVersion.java

@@ -530,8 +530,16 @@ public class ComparableVersion
                 {
                     return 0; // 1-0 = 1- (normalize) = 1
                 }
-                Item first = get( 0 );
+                // Compare the entire list of items with null - not just the first one, MNG-6964
-                return first.compareTo( null );
+                for ( Item i : this )
+                {
+                    int result = i.compareTo( null );
+                    if ( result != 0 )
+                    {
+                        return result;
+                    }
+                }
+                return 0;
             }
             switch ( item.getType() )
             {

maven-artifact/src/test/java/org/apache/maven/artifact/versioning/ComparableVersionTest.java

@@ -295,6 +295,21 @@ public class ComparableVersionTest
         checkVersionsArrayEqual( arr );
     }
 
+    /**
+     * Test <a href="https://issues.apache.org/jira/browse/MNG-6964">MNG-6964</a> edge cases
+     * for qualifiers that start with "-0.", which was showing A == C and B == C but A &lt; B.
+     */
+    public void testMng6964()
+    {
+        String a = "1-0.alpha";
+        String b = "1-0.beta";
+        String c = "1";
+
+        checkVersionsOrder( a, c ); // Now a < c, but before MNG-6964 they were equal
+        checkVersionsOrder( b, c ); // Now b < c, but before MNG-6964 they were equal
+        checkVersionsOrder( a, b ); // Should still be true
+    }
+
     public void testLocaleIndependent()
     {
         Locale orig = Locale.getDefault();