getHash( builder ) {

		if ( this._lightNodesHash === null ) {

			if ( this._lightNodes === null ) this.setupLightsNode( builder );

			const hash = [];

			for ( const lightNode of this._lightNodes ) {

				hash.push( lightNode.getSelf().getHash() );

			}

			this._lightNodesHash = 'lights-' + hash.join( ',' );

		}

		return this._lightNodesHash;

	}
Computes a hash value for identifying the current light nodes setup.

@param {NodeBuilder} builder - A reference to the current node builder.
@return {string} The computed hash.