fix (samples) Import user events BQ, missing UpdateUserEventsJson.java (#494)

* Added UpdateUserEventsJson class.

* 🦉 Updates from OwlBot post-processor

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Author: 2 people

retail/interactive-tutorials/src/main/java/events/setup/UpdateUserEventsJson.java

@@ -0,0 +1,46 @@
+package events.setup;
+
+import java.io.BufferedReader;
+import java.io.FileReader;
+import java.io.FileWriter;
+import java.io.IOException;
+import java.time.LocalDateTime;
+import java.util.ArrayList;
+import java.util.List;
+import org.json.JSONObject;
+
+public class UpdateUserEventsJson {
+
+  public static void main(String[] args) {
+    try {
+      String timestamp = LocalDateTime.now().minusDays(1).toString();
+      String filename = "src/main/resources/user_events.json";
+      updateFields(timestamp, filename);
+      filename = "src/main/resources/user_events_some_invalid.json";
+      updateFields(timestamp, filename);
+    } catch (IOException e) {
+      e.printStackTrace();
+    }
+  }
+
+  private static void updateFields(String timestamp, String filename) throws IOException {
+    List<String> newLines = new ArrayList<>();
+    try (BufferedReader file = new BufferedReader(new FileReader(filename))) {
+      String line = file.readLine();
+      String field = "eventTime";
+      while (line != null) {
+        JSONObject object = new JSONObject(line);
+        object.put(field, timestamp);
+        newLines.add(object.toString());
+        line = file.readLine();
+      }
+    }
+    try (FileWriter file = new FileWriter(filename)) {
+      for (String event : newLines) {
+        file.write(event);
+        file.write("\n");
+      }
+      System.out.println("Successfully updated json file!");
+    }
+  }
+}