allow null value instead of requiring an empty array
allow null value instead of requiring an empty array

MichaelMaar/concrete5,MichaelMaar/concrete5,avdevs/concrete5,MichaelMaar/concrete5,TimDix/concrete5,matt9mg/concrete5,TimDix/concrete5,matt9mg/concrete5,TimDix/concrete5,matt9mg/concrete5,avdevs/concrete5,avdevs/concrete5