In the meantime i figured out, that i can access the properties with JavaObject & Reflection
B4X:
' determine if the first column is sortable
Dim JO As JavaObject
JO = myNode
JO = JO.RunMethod("getColumns", Null)
JO = JO.RunMethod("get", Array As Object(0))
JO = JO.RunMethod("isSortable", Null)