Return true if this SimpleFormatter is currently formatting an array and false otherwise. It is formatting an array if the last open* method overload (openArray or openObject) called on this SimpleFormatter for which the corresponding close* method (respectively, closeArray or closeObject) was openArray. If isFormattingArray() is true, then isFormattingObject() is false. Note that both can be false, at the top‐level initial scope before anything is added/opened or after the first open* call has been closed'