code: @Override
      public <X> EntityType<X> entity(Class<X> paramClass)
      {
          EntityType entityType = entityTypes.get(paramClass);
          if (entityType == null)
          {
              throw new IllegalArgumentException("Not an entity, {class:" + paramClass + "}");
          }
          return entityType;
      }
docs: /*
  (non-Javadoc)
  
  @see javax.persistence.metamodel.Metamodel#entity(java.lang.Class)