S5853 does not handle custom assertions

class MyTestClass {

  @Test
  void nonCompliantTypeTest() {
    MyType myType = new MyType();

    Assertions.assertThat(myType).isNotNull(); // TP: ask to chain methods
    Assertions.assertThat(myType).isEqualTo(new MyType());

    CustomAssert.assertThat(myType).isFoo(); // FN: do not ask to chain methods, while it is possible
    CustomAssert.assertThat(myType).isBar();
  }

  @Test
  void compliantTypeTest() {
    MyType myType = new MyType();

    Assertions.assertThat(myType)
      .isNotNull()
      .isEqualTo(new MyType());

    CustomAssert.assertThat(myType)
      .isFoo()
      .isBar();
  }

  public static class CustomAssert extends AbstractAssert<CustomAssert, MyType> {

    private CustomAssert(MyType actual) {
      super(actual, CustomAssert.class);
    }

    public static CustomAssert assertThat(MyType actual) {
      return new CustomAssert(actual);
    }

    public CustomAssert isFoo() {
      return this;
    }

    public CustomAssert isBar() {
      return this;
    }
  }

  public static class MyType {  }
}