void setRange(
int start,
int end,
Iterable<E> iterable,
[int skipCount = 0]
)

This operation is not supported by an unmodifiable list.

Source

/** This operation is not supported by an unmodifiable list. */
void setRange(int start, int end, Iterable<E> iterable, [int skipCount = 0]) {
  throw new UnsupportedError(
      "Cannot modify an unmodifiable list");
}