public void setMetrics(AWSRequestMetrics metrics) {
        if (metricsIS == null) {
            throw new IllegalStateException(
                    "The underlying input stream must be initialized!");
        }
        metricsIS.setMetrics(metrics);
    }
{@link AWSRequestMetrics} is set per request.
aws-java-sdk-core/src/main/java/com/amazonaws/internal/SdkMetricsSocket.java