private static void writeSourceSetModel(
    @NotNull IonWriter writer,
    @NotNull WriteContext context,
    @NotNull ExternalProject project
  ) {
    writer.setFieldName(PROJECT_SOURCE_SET_MODEL_FIELD);
    GradleSourceSetSerialisationService.writeSourceSetModel(writer, context.sourceSetModel, project.getSourceSetModel());
  }
private static void writeSourceSetModel(
    @NotNull IonWriter writer,
    @NotNull WriteContext context,
    @NotNull ExternalProject project
  )