protected CodeBlock createSub(AddressSetView addrSet, Address entryPt) {
    	
    	if (addrSet.isEmpty()) {
			return null;
		}
			
        Address[] entryPts = new Address[1];
        entryPts[0] = entryPt;

        CodeBlock block = new CodeBlockImpl(this, entryPts, addrSet);
        foundOSubs.addObject(block, addrSet);

        return block;
    }
Create a new Subroutine which has specified address set and entry point.
 Cache the model-O subroutine.
 @param  addrSet contains the address set of the model-O subroutine
 @param entryPt the OSub entry point.
 @return subroutine block that was created
Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/model/block/OverlapCodeSubModel.java