Plugin configuration gets corrupted upon saving the configuration via system console.
Steps to reproduce
Enable plugins (system console -> plugins -> configuration)
Attempt to configure e.g. Jira plugin (system console -> plugins -> jira). Save the form.
Switch to another system console panel and then come back to Jira plugin configuration.
Jira configuration is saved correctly. Values are copied to config.json.
Jira configuration is saved in a corrupted format. If PluginSettings.Plugins.jira tree does not exist in config.json, it is added with null values and wrong capitalization (should be UserName, it is saved as username). If PluginSettings.Plugins.jira tree does exist, settings are preserved but key capitalization is changed to lowercase, making those settings unavailable to plugins.
"Secret": "randomly generated secret",
Problem seems to be about config.json serialization. UI and plugins expect these JSON keys to be CamelCase, but the whole PluginSettings.Plugin tree is automatically converted to lowercase keys upon saving. I can get plugins to work by editing the config manually, however any attempt to save anything in the system console will corrupt existing plugin settings.