Code Inspection: Use preferred style for trailing comma before new line in multiline lists
This code inspection checks that trailing commas in multi-line declarations with multiple items and similar constructs (object, array, and collection initializers, as well as enums and switch expressions) conform to your code style.
Depending on your preferences, it either detects redundant trailing commas or missing trailing commas.
The preferences are configured on the Trailing comma.
page of JetBrains Rider settings Control+Alt+S, under Last modified: 08 March 2021