Update URN rules

Author: Yauhenikapl

core/esmf-aspect-model-aas-generator/src/main/java/org/eclipse/esmf/aspectmodel/aas/AasToAspectModelGenerator.java

@@ -200,10 +200,9 @@ private String iriToReversedHostNameNotation( final IRI iri ) {
       final String[] pathParts = uri.getPath().split( "/" );
       final String path = Arrays.stream( pathParts )
             .filter( StringUtils::isNotBlank )
-            .limit( Math.max( 0, pathParts.length - 2 ) )
             .collect( Collectors.joining( "." ) );
 
-      return reversedHost + ( path.isEmpty() ? "" : "." + path );
+      return reversedHost + "." + path;
    }
 
    private Optional<IRI> iri( final String lexicalRepresentation ) {

core/esmf-aspect-model-urn/src/test/java/org/eclipse/esmf/aspectmodel/urn/AspectModelUrnTest.java

@@ -343,6 +343,19 @@ void validNamespaceTest() throws URISyntaxException {
       assertThat( elementUrnWithDash.getNamespaceMainPart() ).isEqualTo( "org.eclipse.esmf-test" );
    }
 
+   @Test
+   void invalidNamespaceTest() throws URISyntaxException {
+      final URI validNamespaceUrnUnderscore = new URI( "urn:samm:com.bosch.nexeed.digitaltwin:aspect-model:Er?ors:1.1.0#TestAspect" );
+      final AspectModelUrn elementUrnWithUnderscore = AspectModelUrn.fromUrn( validNamespaceUrnUnderscore );
+      assertThat( elementUrnWithUnderscore.getNamespaceMainPart() ).isNotEmpty();
+      assertThat( elementUrnWithUnderscore.getNamespaceMainPart() ).isEqualTo( "org.eclipse.esmf_test" );
+
+      final URI invalidNamespaceUrnDash = new URI( "urn:samm:org.eclipse.esmf-test:0.0.1#TestAspect" );
+      final AspectModelUrn elementUrnWithDash = AspectModelUrn.fromUrn( invalidNamespaceUrnDash );
+      assertThat( elementUrnWithDash.getNamespaceMainPart() ).isNotEmpty();
+      assertThat( elementUrnWithDash.getNamespaceMainPart() ).isEqualTo( "org.eclipse.esmf-test" );
+   }
+
    @Test
    void invalidModelElementNameTest() throws URISyntaxException {
       final URI invalidRootModelElementName = new URI( sammBaseUri + "aspect-model:Er?ors:1.1.0#TestAspect" );