Configuration ignored when defined in multiple sources

Hi.

The plugin configuration is ignored when it is defined in multiple sources. For example, I set the next two config values in .prettierrc

    "braceStyle": "1tbs",
    "singleQuote": true

but the plugin reports the following Resolved config:

{
  "parser": "php",
  "phpVersion": "7.4",
  "plugins": [
    "@prettier/plugin-php"
  ]
}

Then, I noticed I also had some "prettier": {...} configuration in package.json. The new configuration was still ignored after I added the same two config values to the Prettier property in this file. At this point, both configuration sources are the same.

Finally, the new configuration was in effect after I deleted the .prettierrc file.

Start by reproducing the configuration using both .prettierrc and the "prettier" property in package.json, then compare it with the case where .prettierrc is removed. Trace how these two sources are resolved and verify that braceStyle and singleQuote are retained when both sources define them.