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You are right. I opted for the easy and wrong answer, and then tried to explain it away. I have updated my original answer, and I hope you can find it in your heart to forgive me! What you should do is change the type of your instance field to the type LazyOptional<IState>, which you should initialize to LazyOptional.of(() -> STATE_CAPABILITY.getDefaultInstance()), to avoid creating a new LazyOptional every time getCapability() is called. Note that you might have to slightly change some of your other methods to accommodate for the fact that instance now is a LazyOptional. Here is another thread which also discusses why you should cache the capability. I would also recommend taking a look at the LazyOptional class (easiest done via your IDE), since it includes a lot of documentation about why/how it is used.

I usually do it like this: return STATE_CAPABILITY.orEmpty(capability, LazyOptional.of(() -> instance)); EDIT: This is the simple but very wrong answer! As diesieben07 points out further down in the thread, you should absolutely cache the LazyOptional in a field to avoid creating a new LazyOptional every time getCapability() is called.