mobile-buy-sdk-android: return null problem

Hello this is my query.

Storefront.QueryRootQuery query = Storefront.query(
                rootQuery -> rootQuery
                        .node(new ID(productId),nodeQuery -> nodeQuery
                                .onProduct(productQuery -> productQuery
                                        .title()
                                        .description()
                                        .descriptionHtml()
                                        .images(arg -> arg.first(10), imageConnectionQuery -> imageConnectionQuery
                                                .edges(imageEdgeQuery -> imageEdgeQuery
                                                        .node(imageQuery -> imageQuery
                                                                .src()
                                                        )
                                                )
                                        )
                                        .variants(arg -> arg.first(10), variantConnectionQuery -> variantConnectionQuery
                                                .edges(variantEdgeQuery -> variantEdgeQuery
                                                        .node(productVariantQuery -> productVariantQuery
                                                                .price()
                                                                .title()
                                                                .available()
                                                        )
                                                )
                                        )
                                )
                        )
        );

---

but in response; Storefront.Product product = (Storefront.Product) response.data().getNode(); but most data return null.

product.getDescriptionHtml() //null!! …

why? thank you