public void removeChild(@NotNull PackagingElement<?> child) {
    this.update(
      () -> myChildren.remove(child),
      (builder, packagingElementEntity) -> {
        MutableExternalEntityMapping<PackagingElement<?>> mapping = builder.getMutableExternalMapping(PackagingExternalMapping.key);
        WorkspaceEntity entity = mapping.getFirstEntity(child);
        if (entity != null) {
          builder.removeEntity(entity);
        }
      }
    );
  }
public void removeChild(@NotNull PackagingElement<?> child)