The bug

Render controllers have a color field to change the color and opacity of the rendered geometry. This field does absolutely nothing unless the entity has a runtime_identifier of minecraft:warden. Since runtime identifiers are banned in addons (and have annoying side effects anyway), this is not an acceptable solution.

How to reproduce

1. Download and open the attached world
2. Look at the two weird pig things

Expected behavior
They should both be green. Both are identical in every way and are using the exact same render controller.

Observed behavior
Only one is green, the one that is using a warden runtime identifier. The other one completely ignores the value of this field.