public final String finalField = null;
                    public String foo(String bar) { return bar; }
                }
            """
        ) {
            assertHasNoError()
            assertHasWarnings(
                "Field finalField: Nullability changed from nullable to non-nullable",

                    public String foo(String bar) { return bar; }
                    public String[] baz(String bar) { return new String[] {bar}; }
                }
            """
        ) {
            assertHasNoError()
            assertHasWarnings(
                "Method com.example.Source.foo(java.lang.String): Return nullability changed from null-unmarked to non-nullable",

            v2 = """
                class Source {
                    val someVal: String = "some"
                    fun foo(): String = "bar"
                }
            """
        ) {
            assertHasNoError()
            assertHasWarnings(
                "Method com.example.Source.foo(): Return nullability changed from nullable to non-nullable",