The AWS SDKV2 upgrade log no longer warns about instantiation
of the v1 SDK credential providers which are commonly used in
s3a configurations:
* com.amazonaws.auth.EnvironmentVariableCredentialsProvider
* com.amazonaws.auth.EC2ContainerCredentialsProviderWrapper
* com.amazonaws.auth.InstanceProfileCredentialsProvider
When the hadoop-aws module moves to the v2 SDK, references to these
credential providers will be rewritten to their v2 equivalents.
Follow-on to HADOOP-18382. "Upgrade AWS SDK to V2 - Prerequisites"
Contributed by Ahmar Suhail
860c79192a