public FlipperObject keyValuePair(String key, @Nullable String value) {
    // NULLSAFE_FIXME[Parameter Not Nullable]
    return new FlipperObject.Builder().put(key, value).build();
  }
Serialization helper to create {@link FlipperObject}s.
tools/flipper-fresco-plugin/src/main/java/com/facebook/flipper/plugins/fresco/objecthelper/FlipperObjectHelper.java