code: @SuppressWarnings("unchecked")
      @Nullable
      public <T> T executeWithKey(Path<T> path) {
          return executeWithKey((Class<T>) path.getType(), path);
      }
docs: Execute the clause and return the generated key with the type of the given path.
  If no rows were created, null is returned, otherwise the key of the first row is returned.
  
  @param <T>
  @param path path for key
  @return generated key