visitExtension method Null safety

@override StringSink visitExtension(Extension spec, [StringSink? output])

Implementation

@override
StringSink visitExtension(Extension spec, [StringSink? output]) {
  final out = output ??= StringBuffer();
  spec.docs.forEach(out.writeln);
  spec.annotations.forEach((a) => visitAnnotation(a, out));

  out.write('extension');
  if (spec.name != null) {
    out.write(' ${spec.name}');
  }
  visitTypeParameters(spec.types.map((r) => r.type), out);
  if (spec.on != null) {
    out.write(' on ');
    spec.on!.type.accept(this, out);
  }
  out.write(' {');
  spec.fields.forEach((f) {
    visitField(f, out);
    out.writeln();
  });
  spec.methods.forEach((m) {
    visitMethod(m, out);
    if (_isLambdaMethod(m)) {
      out.write(';');
    }
    out.writeln();
  });
  out.writeln(' }');
  return out;
}