assertj: [WithAssertions] ListAssert is broken due to generics fluff

Summary

#775 fixed some discrepancies between WithAssertions and Assertions (shipped in 3.6.0). Unfortunately, I’m afraid that I got some generics wrong leading unwanted regression 😞

Example

public class RemoveMe implements WithAssertions {

  @Test
  public void fixme() {
    List<String> l = new ArrayList<>();
    assertThat(l).contains("foo");
  }
}

Is broken since 3.6.0.

Error:(213, 18) java: no suitable method found for contains(java.lang.String)
    method org.assertj.core.api.AbstractIterableAssert.contains(capture#3 of ? extends java.lang.String...) is not applicable
      (varargs mismatch; java.lang.String cannot be converted to capture#3 of ? extends java.lang.String)
    method org.assertj.core.api.ListAssert.contains(capture#3 of ? extends java.lang.String...) is not applicable
      (varargs mismatch; java.lang.String cannot be converted to capture#3 of ? extends java.lang.String)

This is related to the addition of the following method:

default <T> ListAssert<? extends T> assertThat(final List<? extends T> actual)

I think that return type should be ListAssert<T>, or ListAssert<? super T>, rather than ListAssert<? extends T>.

Do you want me to open a PR to fix it? Should we review the API to spot such mistakes?

Java 8 specific ?

• YES : create Pull Request from the master branch