General contract for object comparision : equals() and hashCode()
<p>There is a point in general contract of equals method, which says if You has defined <code>equals()</code> method then You should also define <code>hashCode()</code> method. And if <code>o1.equals(o2)</code> then this is must <code>o1.hashCode() == o2.hashCode()</code>.</p>

<p>So my question is what if I break this contract? Where can bring fails the situation when <code>o1.equals(o2)</code> but <code>o1.hashCode != o2.hashCode()</code> ?</p>
