addHeader method
Adds a header
to headers for name
.
If headers is null, it is created. If the key does not exist in headers, header
is added for the key.
If the key exists, header
is not added. (To replace a header, access headers directly.)
Implementation
void addHeader(String name, APIHeader? header) {
headers ??= {};
if (!headers!.containsKey(name)) {
headers![name] = header;
}
}