code: @SuppressWarnings("unchecked")
  	<K, E extends PoolableObject<V>> E releaseOwner() {
  		this.owner = null;
  		return (E) this;
  	}
docs: Releases the current owning thread from this Object
  
  @param <K> the Key wrapped Type
  @param <E> the Entry type
  @return PoolableObject for method chaining