VaultHttpClient is not thread safe

[amitisss]

When creating VaultHttpClient in multi threaded environment a System.InvalidOperationException is thrown.

Please Refer to the attached exception log.

Steps to reproduce:

Initialize VaultHttpClient in parallel using several threads.

Solution:

Initialize the VaultHttpClient* in a static block:

    static VaultHttpClient()
    {
        HttpClient.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
    }

VaultHttpClient.Exception.log