2017b >> json = savejson('',data)
name
name =
  0×0 empty char array
item
item = 
  struct with fields:

    Test: {["GML"]  ["XML"]}
level
level =
     0
vargin
varargin =
  1×1 cell array
    {1×1 struct}

name
name =
    'Test'
item
item =
  1×2 cell array
    {["GML"]}    {["XML"]}
level
level =
     1
vargin
varargin =
  1×1 cell array
    {1×1 struct}

name
name =
  0×0 empty char array
item
item = 
    "GML"
level
level =
     2
vargin
varargin =
  1×1 cell array
    {1×1 struct}

txt
txt =
    '		{
     		}'


name
name =
  0×0 empty char array
item
item = 
    "XML"
level
level =
     2
vargin
varargin =
  1×1 cell array
    {1×1 struct}

txt
txt =
    '		{
     		}'


txt
txt =
    '	"Test": [
     		{
     		},
     		{
     		}
     	]'


txt
txt =
    '{
     	"Test": [
     		{
     		},
     		{
     		}
     	]
     }'


json =
    '{
     	"Test": [
     		{
     		},
     		{
     		}
     	]
     }
     '