Provide a 'isNotEmpty()' assertions for Multimap

[spydesk]

So we can assert :

@Test
public void test() {
    Multimap<?, ?> actual = ...;
    assertThat(actual).isNotEmpty();
}

A possible implementation in MultimapAssert:

public void isNotEmpty() {
    Objects.instance().assertNotNull(info, actual);
    if (!actual.isEmpty()) {
        throw failures.failure(info, shouldNotBeEmpty(actual));
    }
}

[joel-costigliola]

I agree, that is useful.

Do you want to contribute this one ?

[spydesk]

Yes, sure !

[spydesk]

Pull request is ready : #10.

Let me know if it is good for you.

[joel-costigliola]

Thanks !