java.lang.IllegalArgumentException: No [EntityType] was found for the key class [MyDynamicEntityClass] in the Metamodel

DynamicHelper helper = new DynamicHelper(JpaHelper.getEntityManager(entityManager).getServerSession());
Class<? extends DynamicEntity> clazz = helper.getType("MyDynamicEntityClass").getJavaClass();
CriteriaQuery query = criteriaBuilder.createQuery(clazz);
Root<? extends DynamicEntity> root = query.from(clazz);

Session session = JpaHelper.getEntityManager(entityManager).getServerSession();
        DynamicClassLoader dynamicClassLoader = DynamicClassLoader.lookup(session);
        Class<?> dynamicEntityClass =
                dynamicClassLoader.createDynamicClass(dynamicClassName);
        JPADynamicTypeBuilder newType = new JPADynamicTypeBuilder(dynamicEntityClass, null, "dynamic_table_name");
        newType.setPrimaryKeyFields("id");
        newType.addDirectMapping("id", String.class, "id");
        
        newType.addDirectMapping("objectId", String.class, "object_id");
        newType.addDirectMapping("description", String.class, "desc");
          jpaDynamicHelper.addTypes(false, false, newType.getType());

    /**
     *  Return the metamodel entity type representing the entity.
     *  @param clazz  the type of the represented entity
     *  @return the metamodel entity type
     *  @throws IllegalArgumentException if not an entity
     */
    public <X> EntityType<X> entity(Class<X> clazz) {
        String key = clazz == null ? null : clazz.getName();
        Object aType = this.entities.get(key);
        if(!(aType instanceof EntityType)) { // will only be true for null or non-metamodel types - as the map only stores EntityType values 
        	entityEmbeddableManagedTypeNotFound(entities, aType, clazz, "Entity", "EntityType");
        }
        return (EntityType<X>) aType;
    }

	Metamodel metamodel = new MetamodelImpl((AbstractSession) helper.getSession());
	((EntityManagerFactoryDelegate) currentEm.getEntityManagerFactory()).setMetamodel(metamodel);