This operation is not supported by an unmodifiable list.
Source
void insertAll(int at, Iterable<E> iterable) {
throw new UnsupportedError(
"Cannot add to an unmodifiable list");
}
This operation is not supported by an unmodifiable list.
void insertAll(int at, Iterable<E> iterable) {
throw new UnsupportedError(
"Cannot add to an unmodifiable list");
}