One line C# code
\n\npublic class Solution {\n    public int[] GetConcatenation(int[] nums) {\n        return nums.Concat(nums).ToArray();\n    }\n}\n
\n```\npublic class Solution {\n    public int[] GetConcatenation(int[] nums) {\n        return nums.Concat(nums).ToArray();\n    }\n}\n```
['Array', 'C#']