composableTypes not working in custom product type XML definition

[fperrin]

Hello,

I'm working with a custom product type which is supposed to be added to bundle products, I found that we are supposed to use the composableType node in the product_types.xml file to set the newly created product type as composable but it doesn't seem to work. I've looked at downloadable products which does exactly that:

<?xml version="1.0"?>
<!--
/**
 * Copyright © 2016 Magento. All rights reserved.
 * See COPYING.txt for license details.
 */
-->
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Catalog:etc/product_types.xsd">
    <type name="downloadable" label="Downloadable Product" modelInstance="Magento\Downloadable\Model\Product\Type" composite="false" isQty="true" canUseQtyDecimals="false" sortOrder="60">
        <priceModel instance="Magento\Downloadable\Model\Product\Price" />
        <indexerModel instance="Magento\Downloadable\Model\ResourceModel\Indexer\Price" />
        <customAttributes>
            <attribute name="refundable" value="false"/>
            <attribute name="is_real_product" value="false"/>
        </customAttributes>
    </type>
    <composableTypes>
        <type name="downloadable" />
    </composableTypes>
</config>

But I'm unable to add my custom product type or a downloadable product to a bundle. To allow my custom product type to be in a bundle product I had to add the following to my product_types.xml file:

<type name="bundle">
    <allowedSelectionTypes>
        <type name="customtype" />
    </allowedSelectionTypes>
</type>

Is this normal behaviour or is this a bug ? I'm asking here before posting an issue on GitHub.

Thank you.