fix: add context field in the payload

src/main/java/com/spotify/confidence/Confidence.java

@@ -101,9 +101,9 @@ public void track(String eventName) {
   }
 
   @Override
-  public void track(String eventName, ConfidenceValue.Struct message) {
+  public void track(String eventName, ConfidenceValue.Struct data) {
     try {
-      client().emit(eventName, getContext(), Optional.of(message));
+      client().emit(eventName, getContext(), Optional.of(data));
     } catch (IllegalStateException e) {
       // swallow this exception
     }

src/main/java/com/spotify/confidence/EventSender.java

@@ -5,7 +5,7 @@
 
 @Beta
 public interface EventSender extends Contextual {
-  public void track(String eventName, ConfidenceValue.Struct message);
+  public void track(String eventName, ConfidenceValue.Struct data);
 
   public void track(String eventName);
 

src/main/java/com/spotify/confidence/EventSenderEngine.java

@@ -4,7 +4,7 @@
 import java.util.Optional;
 
 interface EventSenderEngine extends Closeable {
-  void emit(String name, ConfidenceValue.Struct context, Optional<ConfidenceValue.Struct> message);
+  void emit(String name, ConfidenceValue.Struct context, Optional<ConfidenceValue.Struct> data);
 
   void flush();
 }

src/main/java/com/spotify/confidence/EventSenderEngineImpl.java

@@ -75,13 +75,13 @@ class EventSenderEngineImpl implements EventSenderEngine {
 
   @Override
   public void emit(
-      String name, ConfidenceValue.Struct context, Optional<ConfidenceValue.Struct> message) {
+      String name, ConfidenceValue.Struct context, Optional<ConfidenceValue.Struct> data) {
     if (intakeClosed) {
       log.warn("EventSenderEngine is closed, dropping event {}", name);
       return;
     }
     final Event event =
-        EventUploader.event(name, context, message).setEventTime(clock.getTimestamp()).build();
+        EventUploader.event(name, context, data).setEventTime(clock.getTimestamp()).build();
     if (estimatedMemoryConsumption.get() + event.getSerializedSize() > maxMemoryConsumption) {
       log.warn("EventSenderEngine is overloaded, dropping event {}", name);
       return;

src/main/java/com/spotify/confidence/EventUploader.java

@@ -2,19 +2,23 @@
 
 import com.google.protobuf.Struct;
 import com.spotify.confidence.events.v1.Event;
+import java.util.HashMap;
 import java.util.List;
+import java.util.Map;
 import java.util.Optional;
 import java.util.concurrent.CompletableFuture;
 
 interface EventUploader {
   static Event.Builder event(
-      String name, ConfidenceValue.Struct context, Optional<ConfidenceValue.Struct> message) {
+      String name, ConfidenceValue.Struct context, Optional<ConfidenceValue.Struct> data) {
+    final Map<String, ConfidenceValue> map = new HashMap<>(Map.of());
+    final ConfidenceValue.Struct dataStruct = data.orElse(ConfidenceValue.Struct.EMPTY);
+    map.putAll(dataStruct.asMap());
+    map.put("context", context);
+
     return Event.newBuilder()
         .setEventDefinition(EventSenderEngineImpl.EVENT_NAME_PREFIX + name)
-        .setPayload(
-            Struct.newBuilder()
-                .putAllFields(context.asProtoMap())
-                .putAllFields(message.orElse(ConfidenceValue.Struct.EMPTY).asProtoMap()));
+        .setPayload(Struct.newBuilder().putAllFields(ConfidenceValue.of(map).asProtoMap()));
   }
 
   CompletableFuture<Boolean> upload(List<Event> events);

src/test/java/com/spotify/confidence/EventSenderEngineTest.java

@@ -110,7 +110,19 @@ public void testOverlappingKeysInPayload() throws InterruptedException {
                         "a",
                         Value.newBuilder().setNumberValue(0).build(),
                         "message",
-                        Value.newBuilder().setNumberValue(1).build()))
+                        Value.newBuilder().setNumberValue(1).build(),
+                        "context",
+                        Value.newBuilder()
+                            .setStructValue(
+                                Struct.newBuilder()
+                                    .putAllFields(
+                                        Map.of(
+                                            "a",
+                                            Value.newBuilder().setNumberValue(2).build(),
+                                            "message",
+                                            Value.newBuilder().setNumberValue(3).build()))
+                                    .build())
+                            .build()))
                 .build());
   }
 

src/test/java/com/spotify/confidence/FakeEventSenderEngine.java

@@ -25,8 +25,8 @@ public void close() throws IOException {
 
   @Override
   public void emit(
-      String name, ConfidenceValue.Struct context, Optional<ConfidenceValue.Struct> message) {
-    events.add(event(name, context, message).setEventTime(clock.getTimestamp()).build());
+      String name, ConfidenceValue.Struct context, Optional<ConfidenceValue.Struct> data) {
+    events.add(event(name, context, data).setEventTime(clock.getTimestamp()).build());
   }
 
   @Override

src/test/java/com/spotify/confidence/GrpcEventUploaderTest.java

@@ -98,7 +98,13 @@ public void testMapsSingleEventBatchToProtobuf() throws ExecutionException, Inte
 
     final Map<String, com.google.protobuf.Value> fieldsMap = protoEvent.getPayload().getFieldsMap();
     assertThat(fieldsMap.get("messageKey").getStringValue()).isEqualTo("value_1");
-    assertThat(fieldsMap.get("contextKey").getStringValue()).isEqualTo("value_1");
+    assertThat(
+            fieldsMap
+                .get("context")
+                .getStructValue()
+                .getFieldsOrThrow("contextKey")
+                .getStringValue())
+        .isEqualTo("value_1");
   }
 
   @Test
@@ -130,7 +136,13 @@ public void testMapsMultiEventBatchToProtobuf() {
       final Map<String, com.google.protobuf.Value> fieldsMap =
           protoEvent.getPayload().getFieldsMap();
       assertThat(fieldsMap.get("messageKey").getStringValue()).isEqualTo("value_m" + (i + 1));
-      assertThat(fieldsMap.get("contextKey").getStringValue()).isEqualTo("value_c" + (i + 1));
+      assertThat(
+              fieldsMap
+                  .get("context")
+                  .getStructValue()
+                  .getFieldsOrThrow("contextKey")
+                  .getStringValue())
+          .isEqualTo("value_c" + (i + 1));
     }
   }