private static void queueDestReference(LinkedList<CodeBlockReferenceImpl> blockRefQueue, CodeBlock destBlock, 
    	Address toAddr, Address fromAddr, FlowType flowType, TaskMonitor monitor) {
    	
    	if (blockRefQueue == null)
    		return;
    	
    	blockRefQueue.add(new CodeBlockReferenceImpl(null, destBlock, flowType, toAddr, fromAddr));
    	
    }
Create a new block reference and add it to the queue.
@param blockRefQueue the CodeBlockReference queue, may be null
@param destBlock reference/destination block
@param toAddr reference destination address
@param fromAddr reference source address
@param flowType reference flow type
@param monitor task monitor which allows user to cancel operation.
Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/model/block/SimpleSourceReferenceIterator.java