secret = a
secret = ${?SECRET_A}
secrets = ["b", "c"]
secrets = [${?SECRET_B}, ${?SECRET_C}]
myList = ${MY_LIST[]}
myOptionalList = ${?MY_LIST[]}
myOptionalUndefinedList = ${?UNDEFINED_LIST[]}
numList = ${NUM_LIST[]}
# list concatenation with env var list expansion
prependedList = ["x", "y"] ${?MY_LIST[]}
appendedList = ${?MY_LIST[]} ["x", "y"]
selfAppendedList = ["x"]
selfAppendedList = ${?selfAppendedList} ${?MY_LIST[]}
appendedUndefined = ["x", "y"] ${?UNDEFINED_LIST[]}