ot::Coap::Option::Iterator::Init() method
Initializes the iterator to iterate over CoAP Options in a CoAP message. The iterator MUST be initialized before any other methods are used, otherwise its behavior is undefined. After initialization, the iterator is either updated to point to the first option, or it is marked as done (i.e., `IsDone()` returns `true`) when there is no option or if there is a parse error.
Arguments
aMessage
The CoAP message.
Return value
kErrorNone Successfully initialized. Iterator is either at the first option or done. kErrorParse CoAP Option header in @p aMessage is not well-formed.