public boolean hasSettableCollection() {
    for (ValueAttribute a : getSettableAttributes()) {
      if (a.isCollectionType()) {
        return true;
      }
    }
    return false;
  }
Means object hashcode is cached at some point. Either lazily (on first access)
or eagerly (during construction).
@see #isUseLazyhash()
@see #isUsePrehashed()
value-processor/src/org/immutables/value/processor/meta/ValueType.java