I’m sorry to have to say this, but it’s not supported
The first item of the array will be used to determine the type of the items in the array. Mixed arrays are unsupported. A mixed array is an array with entries of different data types (e.g. string and integer). In the tree structure, a error will appear that you cannot use mixed arrays in your mappings.
you will need to use some java lib for parsing.
Maybe this module can help (a java lib for parsing):