UTF-8 Umlauts in YML files break on rendering

Problem/Motivation

When using cl_server to develop components, we try to use real content from our client's websites, which sometimes contains special characters like umlauts (ä, ö, ü). Those values get sent to the drupal backend and get rendered by cl_components. When doing so, the module puts the sent values through Json::encode in ComponentElement.php on line 115. Since drupal's Json::encode does not respect umlauts, they beak to Strings like "U00f6".

Steps to reproduce

Create a component with umlauts like "ö" in a demo content string when using cl_server and storybook for development.

Proposed resolution

Since the umlauts get sent to the drupal correctly but break on Json::encode while rendering and the core Json class does not provide a flag for this, replace

Json::encode($context)

with

json_encode($context, JSON_HEX_TAG | JSON_HEX_APOS | JSON_HEX_AMP | JSON_HEX_QUOT | JSON_UNESCAPED_UNICODE)

The flag "JSON_UNESCAPED_UNICODE" makes sure, that the encoding of the umlauts keeps working.

Remaining tasks

Review / Merge

User interface changes

None

API changes

None

Data model changes

None