getHeader method
Implementation
String? getHeader(String headerKey, {String? def}) {
var val = headers[headerKey];
if (val != null) return val;
headerKey = headerKey.trim().toLowerCase();
val = headers[headerKey];
if (val != null) return val;
for (var k in headers.keys) {
var kLC = k.toLowerCase();
if (kLC == headerKey) {
return headers[k];
}
}
return def;
}