[ML] Close sample stream in post_data endpoint (elastic#43235)

A static code analysis revealed that we are not closing
the input stream in the post_data endpoint.  This
actually makes no difference in practice, as the
particular InputStream implementation in this case is
org.elasticsearch.common.bytes.BytesReferenceStreamInput
and its close() method is a no-op. However, it is good
practice to close the stream anyway.

Author: droberts195

x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/action/TransportPostDataAction.java

@@ -17,6 +17,7 @@
 import org.elasticsearch.xpack.ml.job.process.autodetect.params.DataLoadParams;
 import org.elasticsearch.xpack.ml.job.process.autodetect.params.TimeRange;
 
+import java.io.InputStream;
 import java.util.Optional;
 
 public class TransportPostDataAction extends TransportJobTaskAction<PostDataAction.Request, PostDataAction.Response> {
@@ -37,8 +38,8 @@ protected void taskOperation(PostDataAction.Request request, TransportOpenJobAct
                                  ActionListener<PostDataAction.Response> listener) {
         TimeRange timeRange = TimeRange.builder().startTime(request.getResetStart()).endTime(request.getResetEnd()).build();
         DataLoadParams params = new DataLoadParams(timeRange, Optional.ofNullable(request.getDataDescription()));
-        try {
-            processManager.processData(task, analysisRegistry, request.getContent().streamInput(), request.getXContentType(),
+        try (InputStream contentStream = request.getContent().streamInput()) {
+            processManager.processData(task, analysisRegistry, contentStream, request.getXContentType(),
                     params, (dataCounts, e) -> {
                 if (dataCounts != null) {
                     listener.onResponse(new PostDataAction.Response(dataCounts));