Why does Guava's ImmutableList have so many overloaded of() methods?

I was just looking at Guava's ImmutableList and I noticed that the of() method was overloaded 12 times.

It looks to me that all they needed was:

static <E> ImmutableList<E> of();
static <E> ImmutableList<E> of(E element); // not even necessary
static <E> ImmutableList<E> of(E... elements);

What's the reason for having so many similar variations?