.filter(outputPropertyNames -> !outputPropertyNames.isEmpty())
            .map(ImmutableSet::asList)
            .orElse(null);
    }

    @Nullable
    public byte[] getHashBytes() {
        return getKey()
            .map(BuildCacheKey::toByteArray)
            .orElse(null);
    }

    @Override
    public Object getCustomOperationTraceSerializableModel() {