Update README.md (aws#363)

* Update README.md

README.md

@@ -228,6 +228,71 @@ try {
 ```
 Note that in the closure-based example above, exceptions are intercepted automatically.
 
+### Oversampling Mitigation
+Oversampling mitigation allows you to ignore a parent segment/subsegment's sampled flag and instead sets the subsegment's sampled flag to false.
+This ensures that downstream calls are not sampled and this subsegment is not emitted.
+
+```Java
+public class Handler implements RequestHandler<SQSEvent, String> {
+    public Handler() {
+    }
+
+    @Override
+    public String handleRequest(SQSEvent event, Context context) {
+        AWSXRay.beginSubsegmentWithoutSampling("Processing Event");
+
+        AmazonSQS sqs = AmazonSQSClientBuilder.defaultClient();
+
+        ListQueuesResult lq_result = sqs.listQueues();
+
+        System.out.println("Your SQS Queue URLs:");
+
+        for (String url : lq_result.getQueueUrls()) {
+            System.out.println(url);
+        }
+
+        AWSXRay.endSubsegment();
+
+        return "Success";
+    }
+}
+```
+
+The code below demonstrates overriding the sampled flag based on the SQS message.
+
+```java
+public class Handler implements RequestHandler<SQSEvent, String> {
+    public Handler() {
+    }
+
+    @Override
+    public String handleRequest(SQSEvent event, Context context) {
+
+        int i = 1;
+
+        for (SQSMessage message: event.getRecords()) {
+
+            // Check if the message is sampled
+            if (SQSMessageHelper.isSampled(message)) {
+                AWSXRay.beginSubsegment("Processing Message - " + i);
+            } else {
+                AWSXRay.beginSubsegmentWithoutSampling("Processing Message - " + i);
+            }
+
+            i++;
+
+            // Do your procesing work here
+            System.out.println("Doing processing work");
+
+            // End your subsegment
+            AWSXRay.endSubsegment();
+        }
+
+        return "Success";
+    }
+}
+```
+
 ## Integration with ServiceLens
 
 As of version 2.4.0, the X-Ray SDK for Java is integrated with [CloudWatch ServiceLens](https://docs.aws.amazon.com/AmazonCloudWatch/latest/monitoring/ServiceLens.html). This allows you to use a wide range of new observability features which connect your traces, logs, and metrics in one place.