openDatabase method Null safety

@JSName('openDatabase')
@SupportedBrowser(SupportedBrowser.CHROME)
@SupportedBrowser(SupportedBrowser.SAFARI)
@Creates('SqlDatabase')

SqlDatabase openDatabase (

String name,
String version,
String displayName,
int estimatedSize,
[DatabaseCallback? creationCallback]

)

@Creates('SqlDatabase'), @JSName('openDatabase'), @SupportedBrowser(SupportedBrowser.CHROME), @SupportedBrowser(SupportedBrowser.SAFARI)

Implementation

@JSName('openDatabase')
@SupportedBrowser(SupportedBrowser.CHROME)
@SupportedBrowser(SupportedBrowser.SAFARI)
@Creates('SqlDatabase')
SqlDatabase openDatabase(
    String name, String version, String displayName, int estimatedSize,
    [DatabaseCallback? creationCallback]) {
  var db;
  if (creationCallback == null)
    db = _openDatabase(name, version, displayName, estimatedSize);
  else
    db = _openDatabase(
        name, version, displayName, estimatedSize, creationCallback);

  applyExtension('Database', db);

  return db;
}