addObserver method
Implementation
void addObserver(OSMMixinObserver osmMixinObserver) {
if (!_mixinObserver.contains(osmMixinObserver)) {
_mixinObserver.add(osmMixinObserver);
}
}
void addObserver(OSMMixinObserver osmMixinObserver) {
if (!_mixinObserver.contains(osmMixinObserver)) {
_mixinObserver.add(osmMixinObserver);
}
}