AssertJ recipes should not change `assertThat(null== a).isEqualTo(true)` to `assertThat(null).isSameAs(a)`

## Compilation error
`assertThat(null== a).isEqualTo(true)` => `assertThat(null).isSameAs(a);`

## Better
`assertThat(null== a).isEqualTo(true)` => `assertThat(a).isNull()`