Address few nits in transport-runtime (#4925)

Author: rlazo

transport/transport-runtime/src/main/java/com/google/android/datatransport/runtime/scheduling/jobscheduling/Uploader.java

@@ -38,6 +38,7 @@
 import com.google.android.datatransport.runtime.time.Clock;
 import com.google.android.datatransport.runtime.time.Monotonic;
 import com.google.android.datatransport.runtime.time.WallTime;
+import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
@@ -113,6 +114,7 @@ public void upload(TransportContext transportContext, int attemptNumber, Runnabl
   }
 
   @RestrictTo(RestrictTo.Scope.LIBRARY_GROUP)
+  @CanIgnoreReturnValue
   public BackendResponse logAndUpdateState(TransportContext transportContext, int attemptNumber) {
     TransportBackend backend = backendRegistry.get(transportContext.getBackendName());
     long maxNextRequestWaitMillis = 0;

transport/transport-runtime/src/main/java/com/google/android/datatransport/runtime/scheduling/persistence/SQLiteEventStore.java

@@ -680,13 +680,15 @@ public ClientMetrics loadClientMetrics() {
                                 .build());
                   }
                   populateLogSourcesMetrics(clientMetricsBuilder, metricsMap);
-                  clientMetricsBuilder.setWindow(getTimeWindow());
-                  clientMetricsBuilder.setGlobalMetrics(getGlobalMetrics());
-                  clientMetricsBuilder.setAppNamespace(packageName.get());
-                  return clientMetricsBuilder.build();
+                  return clientMetricsBuilder
+                      .setWindow(getTimeWindow())
+                      .setGlobalMetrics(getGlobalMetrics())
+                      .setAppNamespace(packageName.get())
+                      .build();
                 }));
   }
 
+  @SuppressWarnings("CheckReturnValue")
   private void populateLogSourcesMetrics(
       ClientMetrics.Builder clientMetricsBuilder, Map<String, List<LogEventDropped>> metricsMap) {
     for (Map.Entry<String, List<LogEventDropped>> entry : metricsMap.entrySet()) {

transport/transport-runtime/transport-runtime.gradle

@@ -117,6 +117,7 @@ dependencies {
     }
 
     compileOnly "com.google.auto.value:auto-value-annotations:1.6.6"
+    compileOnly "com.google.errorprone:error_prone_annotations:2.9.0"
 
     annotationProcessor "com.google.auto.value:auto-value:1.6.5"
     annotationProcessor 'com.google.dagger:dagger-compiler:2.27'