One weird trick to cache single-layer blurs

                const bool requiresHolePunch =

                        mHolePunchCandidate && mHolePunchCandidate->requiresHolePunch();

                if (!requiresHolePunch) {

                    // If we don't require a hole punch, then treat solid color layers at the front

                    // to be "cheap", so remove them from the candidate cached set.

                if (!requiresHolePunch && mBlurringLayer == nullptr) {

                    // If we don't require a hole punch and we're not being blurred, then treat

                    // solid color layers at the front to be "cheap", so remove them from the

                    // candidate cached set.

                    while (mNumSets > 1 && mStart->getLayerCount() == 1 &&

                           mStart->getFirstLayer().getBuffer() == nullptr) {

                        mStart++;

                        mNumSets--;

                    }

                    // Only allow for single cached sets if a hole punch is required. If we're here,

                    // then we don't require a hole punch, so don't build a run.

                    // Only allow for single cached sets if a hole punch or blur is required.

                    // Neither is true if we're here.

                    if (mNumSets <= 1) {

                        return std::nullopt;

                    }