code: public void setReferenceResolver (ReferenceResolver referenceResolver) {
  		if (referenceResolver == null) throw new IllegalArgumentException("referenceResolver cannot be null.");
  		this.references = true;
  		this.referenceResolver = referenceResolver;
  		if (TRACE) trace("kryo", "Reference resolver: " + referenceResolver.getClass().getName());
  	}
docs: Sets the reference resolver and enables references.