Rest API Exposure

[CHEWX]

Describe the bug
Using core blocks such as core/image, firstly this is not exposed to the Rest API. So If I was to expose using parse_blocks() and rest_prepare_cpt_project there is no way to get the caption?

Expected behavior
To have access to captions as an attribute like images.

Screenshots

Array
(
    [blockName] => core/image
    [attrs] => Array
        (
            [id] => 16
        )

    [innerBlocks] => Array
        (
        )

    [innerHTML] => 
<figure class="wp-block-image"><img src="http://wordpress.test/wp-content/uploads/2019/07/image-1-1024x730.jpg" alt="" class="wp-image-16"/><figcaption>This is a caption</figcaption></figure>

    [innerContent] => Array
        (
            [0] => 
<figure class="wp-block-image"><img src="http://wordpress.test/wp-content/uploads/2019/07/image-1-1024x730.jpg" alt="" class="wp-image-16"/><figcaption>This is a caption</figcaption></figure>

        )

)

Desktop (please complete the following information):
All.

Smartphone (please complete the following information):
All.

[skorasaurus]

this may be fulfilled in #2649

[mtias]

Tracked in https://core.trac.wordpress.org/ticket/53603