AmazonS3Client's constructor overwrites credentials in caller provided AmazonS3Config object

[ryagin]

Describe the bug

Certain overloads of AmazonS3Client constructor accept both login/password (awsAccessKeyId/awsSecretAccessKey) and an instance of AmazonS3Config object.

Down the call chain, in AmazonServiceClient, the config object is modified by overwriting DefaultAWSCredentials:
if(credentials != null) config.DefaultAWSCredentials = credentials;

If several instances of AmazonS3Client are created with same config instance but different credentials, previously set credentials will be overwritten by latest call.

Regression Issue

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Expected Behavior

Common expectation is that config object created by the user code should not be modified by the library code.

Current Behavior

Config object created by the user code is modified by the library code, causing confusion.

Reproduction Steps

`
var config = new AmazonS3Config();

var client1 = new AmazonS3Client(username1, password1, config);

var client2 = new AmazonS3Client(username2, password2, config);

// client1 now inadvertently uses username2/password2
`

Possible Solution

Save login/password independently from configuration or create private copy of configuration object.

Additional Information/Context

No response

AWS .NET SDK and/or Package version used

AWSSDK.S3 4.0.4.2, but current code in main is still affected

Targeted .NET Platform

All

Operating System and version

All

[afroz429]

Thanks for reporting the issue. The team will review tomorrow and provide an update.