...internal.Iterables is used in Asserts generated by assertj-assertions-generator (java9)

#### Summary
Hi,
I am migrating from java 8 to 17 and had big trouble getting the generated assertions to work (actually is does not work at all, is it dead?)

But even with great hacks I cannot get arround that the generated code imports the internal class `org.assertj.core.internal.Iterables` which is (of course) not exported by assertj-core. Could this become public? Or could the code-generator be updated? Which btw has medium CVEs in it's dependencies.

#### Example

```java
import org.assertj.core.internal.Iterables;
//this is part of the generated code
public YAssert hasXs(X... xs) {
// check that actual Y we want to make assertions on is not null.
isNotNull();

// check that given X varargs is not null.
if (x== null) failWithMessage("Expecting x parameter not to be null.");

// check with standard error message, to set another message call: info.overridingErrorMessage("my error message");
Iterables.instance().assertContains(info, actual.getX(), xs);

// return the current assertion for method chaining
return this;
}
```

Package 'org.assertj.core.internal' is declared in module 'org.assertj.core', which does not export it to module 'my.assertions'

In other words: Is does not compile in Java > 8 which renders the complete code generation useless.

Beginne mit der Untersuchung des Pfads zur Assertion-Generierung, der Importe von org.assertj.core.internal.Iterables erzeugt, und reproduziere anschließend den Kompilierungsfehler des generierten Codes in einem modularen Java-9+-Projekt. Als erledigt gilt die Aufgabe, wenn die generierten Assertions nicht mehr von der nicht exportierten internen Klasse abhängen und unter Java 9 und später erfolgreich kompiliert werden.

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