getMetaType abstract method
Extracts the metadata type from a raw Meta map.
Retrieves the type identifier (e.g., "btc", "eth") from a raw Meta map with a fallback default value if the type field is missing.
meta is the raw Meta map containing type value.
defaultValue is the fallback value if type is not found.
Returns the extracted Meta type (or defaultValue if not present).
Implementation
String? getMetaType(Mapping meta, [String? defaultValue]);