improved code coverage per Sonar

Author: ddsharpe

imagetool/src/test/java/com/oracle/weblogic/imagetool/aru/VersionTest.java

@@ -42,6 +42,11 @@ void integerComparison() {
         compareDifferingVersions("13.9.4.2.9", "13.9.4.2.10");
     }
 
+    @Test
+    void nullVersion() {
+        compareDifferingVersions(null, "1.2.3");
+    }
+
     @Test
     void nonNumericVersion() {
         assertThrows(NumberFormatException.class, () -> new Version("1.A.4"));
@@ -63,6 +68,7 @@ void equalObjects() {
         assertEquals(a, b);
         assertEquals(b, a);
         assertEquals(a, a);
+        assertNotEquals(a, null);
     }
 
     @Test