Support constructing JwtAuthenticator with token includes Bearer prefix predefined (#1949)

Co-authored-by: Niv Meshorer <niv@word-line.com>

Author: nivmeshorer

src/RestSharp/Authenticators/JwtAuthenticator.cs

@@ -28,7 +28,7 @@ public JwtAuthenticator(string accessToken) : base(GetToken(accessToken)) { }
     [PublicAPI]
     public void SetBearerToken(string accessToken) => Token = GetToken(accessToken);
 
-    static string GetToken(string accessToken) => $"Bearer {Ensure.NotEmpty(accessToken, nameof(accessToken))}";
+    static string GetToken(string accessToken) => Ensure.NotEmpty(accessToken, nameof(accessToken)).StartsWith("Bearer ") ? accessToken : $"Bearer {accessToken}";
 
     protected override ValueTask<Parameter> GetAuthenticationParameter(string accessToken)
         => new(new HeaderParameter(KnownHeaders.Authorization, accessToken));

test/RestSharp.Tests/JwtAuthTests.cs

@@ -34,6 +34,20 @@ public async Task Can_Set_ValidFormat_Auth_Header() {
         Assert.True(authParam.Type == ParameterType.HttpHeader);
         Assert.Equal(_expectedAuthHeaderContent, authParam.Value);
     }
+    
+    [Fact]
+    public async Task Can_Set_ValidFormat_Auth_Header_With_Bearer_Prefix() {
+        var client  = new RestClient { Authenticator = new JwtAuthenticator($"Bearer {_testJwt}") };
+        var request = new RestRequest();
+
+        //In real case client.Execute(request) will invoke Authenticate method
+        await client.Authenticator.Authenticate(client, request);
+
+        var authParam = request.Parameters.Single(p => p.Name.Equals(KnownHeaders.Authorization, StringComparison.OrdinalIgnoreCase));
+
+        Assert.True(authParam.Type == ParameterType.HttpHeader);
+        Assert.Equal(_expectedAuthHeaderContent, authParam.Value);
+    }
 
     [Fact]
     public async Task Check_Only_Header_Authorization() {