private TypeExtractor getTypeExtractor() {
    if (typeExtractor == null) {
      this.typeExtractor = new TypeExtractor(Proto.typeFactory(), (Parameterizable) element);
    }
    return typeExtractor;
  }
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