[main-lts] Added so equals and hashcode is generated in models.

[github-actions]

Backport: #920

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I have added so equals and hashCode is generated to the models. It's possible to disabled it if someone doesn't want it.

@ricardozanini I created an new branch and pull request, it was easier and faster for me to do that.

The result looks like this:

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;

        Animal model = (Animal) o;

        return Objects.equals(born, model.born) &&
        Objects.equals(deceased, model.deceased);
    }

    @Override
    public int hashCode() {
        return Objects.hash(born,
        deceased);
    }

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