Hey there! it does indeed accept JSON. Below is a sample for reference:
<filtermetadata>
<parameter uid="0" value="true"></parameter>
<parameter uid="1" value="true"></parameter>
<parameter uid="2" value="true"></parameter>
<parameter uid="3" value="true"></parameter>
<parameter uid="4" value="true"></parameter>
</filtermetadata>
json version:
"filtermetadata":
{
"parameters":
{
"parameter":
[
{
"@uid":"0",
"@value":"true"
},
{
"@uid":"1",
"@value":"true"
},
{
"@uid":"2",
"@value":"true"
},
{
"@uid":"3",
"@value":"true"
},
{
"@uid":"4",
"@value":"true"
}
]