Nested paragraph support

@Maintainer: Any plan to merge this after 11 months?
Would be great to finish this. We're also working on finishing 🐛 Cloning Entities with Layout Paragraphs breaks structure and moves subparagraphs into Disabled Items RTBC

Thank you :)

Here's the static patch from MR!1 as of now!

I tried to reproduce this as I have several nested paragraphs and thought I would need this patch. But at the moment I cannot produce any cloning issues with those nested paragraphs.

For me, everything is fine without the patch.

Linking 🐛 It is not possible to react to an entity being duplicated Needs work and ✨ Paragraph Library supports Entity Clone module Needs work since that would allow the paragraphs module to take care of the clones generically when an entity is duplicated.

We are experiencing a similar issue.

We have a client who is creating templates for complicate pages with nested paragraphs. They have for example accordion type paragraphs which contain multiple levels of paragraphs.

We were investigating an issue where it seems like editing two different clones makes the content from the other clone disappear until the content is saved again. I presume that the parent paragraph id is always the same and it gets mixed up between the contents.

We will test if this patch will solve the issue for us.

A small update. I tried today to reproduce the issue in my local but so far I have not been able to. I would like to ask for help from others here to help me understand that what database tables might be affected if a nested paragraph is cloned and the parent paragraph id is not duplicated correctly?

I did however update both Paragraphs and Quick node clone to latest version which might also affect my testing. I will also try with the older version.

I will also try to explain our structure a bit more to understand the situation.

We have some event content types where there is a nested paragraph like this:
- Section
-- Accordion
--- Accordion item
--- Accordion item
- Section
-- Accordion
--- Accordion item
--- Accordion item

What happens is that there are several contents which are cloned from the same template. And randomly it happens so that the content first looks fine but then suddently the Section and Accordion paragraphs seem to be intact but the Accordion items are missing. And resaving the clone brings them back.

Also notable is that we are using Asymmetric translations widget → module to bring better support for different language versions.