code: public BuildableType.Builder partialToBuilder(PartialToBuilderMethod partialToBuilder) {
      this.partialToBuilder = Objects.requireNonNull(partialToBuilder);
      _unsetProperties.remove(Property.PARTIAL_TO_BUILDER);
      return (BuildableType.Builder) this;
    }
docs: Sets the value to be returned by {@link BuildableType#partialToBuilder()}.
  
  @return this {@code Builder} object
  @throws NullPointerException if {@code partialToBuilder} is null