code: @Deprecated
      public Regions getKmsRegion() {
          if (awskmsRegion == null) return null;
          return Regions.fromName(awskmsRegion.getName());
      }
docs: Returns the the KMS region explicitly specified for the AWS KMS client
  when such client is internally instantiated; or null if no explicit KMS
  region is specified. This KMS region parameter is ignored when the AWS
  KMS client of the S3 encryption client is explicitly passed in by the
  users, instead of being implicitly created.
  
  @Deprecated This method is not forward compatible. Throws
  IllegalArguementException when a new region is encountered.
  
  @use {@link #getAwsKmsRegion()} instead