Gets all settings for a key, for which valid values are application-specific (Confluence maps this to space keys,
JIRA to project keys, and FishEye to repository keys, for example). To store settings for other keys,
createGlobalSettings should be used, and the keys should be sensibly namespaced by the plugin.
key - the key, can be null to retrieve global settings
Gets all global settings. This is useful to store settings against arbitrary keys. When storing settings against
arbitrary keys, plugins are advised to namespace the key with something unique to the plugin (for example
"com.example.plugin:key-I-would-like-to-use" ) to avoid clashes with other keys.