protected EObject loadHutn(final String content) throws Exception {
        final var ecoreResourceSet = new ResourceSetImpl();
        ecoreResourceSet.getResourceFactoryRegistry().getExtensionToFactoryMap().put("ecore", new XMIResourceFactoryImpl());
        ecoreResourceSet.getPackageRegistry().put(ImPackage.eINSTANCE.getNsURI(), ImPackage.eINSTANCE);

        try (var inModel = new HutnModel("name", content)) {
            // ... ?
            inModel.dispose();
            inModel.close();
        }
        return ecoreResourceSet.getContents().get(0);
    }

    static final ImPackage PCK = ImPackage.eINSTANCE;

    protected EObject loadHutn(final String content) throws Exception {
        final var ecoreResourceSet = new ResourceSetImpl();
        ecoreResourceSet.getResourceFactoryRegistry().getExtensionToFactoryMap().put(
                PCK.getNsPrefix(),
                new XMIResourceFactoryImpl());
        ecoreResourceSet.getPackageRegistry().put(PCK.getNsURI(), PCK);

        EObject result = null;
        try (var inModel = new HutnModel("name.im", content)) {
            inModel.load();

            result = (EObject) inModel.allContents().iterator().next(); // java.util.NoSuchElementException here
            inModel.dispose();
        }
        return result;
    }

    @Test
    void testName() throws Exception {

        loadHutn(String.format("""
                @Spec {
                  metamodel "%s" {
                    nsUri: "%s"
                  }
                }

                ImModel {
                }
                """, PCK.getNsPrefix(), PCK.getNsURI()));
}

<?xml version="1.0" encoding="UTF-8"?>
<ecore:EPackage xmi:version="2.0" xmlns:xmi="http://www.omg.org/XMI" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:ecore="http://www.eclipse.org/emf/2002/Ecore" name="Im" nsURI="https://www.acme.com/im" nsPrefix="Im">
  <eClassifiers xsi:type="ecore:EClass" name="Project">
    <eStructuralFeatures xsi:type="ecore:EAttribute" name="name" lowerBound="1" eType="ecore:EDataType http://www.eclipse.org/emf/2002/Ecore#//EString"/>
  </eClassifiers>
</ecore:EPackage>

@Spec {
  metamodel "Im" {
    nsUri: "https://www.acme.com/im"
   }
}
Project {
  name: "MyProject"
}

public static void main(String[] args) throws Exception {

  EPackage.Registry.INSTANCE.put(ImPackage.eNS_URI, ImPackage.eINSTANCE);

  HutnModel model = new HutnModel();
  StringProperties properties = new StringProperties();
  properties.put(HutnModel.PROPERTY_SOURCE_FILE, new File("model.hutn").getAbsolutePath());
  properties.put(HutnModel.PROPERTY_READONLOAD, "true");
  model.load(properties);

  System.out.println(model.allContents());
}

@Spec {
  metamodel "Im" {
    nsUri: "https://www.acme.com/im"
  }
}

im {
  Project {
    name: "MyProject"
  }
}