beginStructure 
  Decodes the beginning of the nested structure in a serialized form and returns CompositeDecoder responsible for decoding this very structure.
Typically, classes, collections and maps are represented as a nested structure in a serialized form. E.g. the following JSON
{
    "a": 2,
    "b": { "nested": "c" }
    "c": [1, 2, 3],
    "d": null
}Content copied to clipboard
has three nested structures: the very beginning of the data, "b" value and "c" value.