@Override
	public void addMnemonicReference(Address refAddr, RefType refType, SourceType sourceType) {
		validate(lock);
		refMgr.addMemoryReference(address, refAddr, refType, sourceType, MNEMONIC);
	}
Perform any refresh necessary and determine if this code unit has been deleted.
If a record has been provided, it may be used to facilitate a refresh without
performing a record query from the database
@param record optional record which corresponds to code unit.  A null record
does NOT indicate existence and a record query may be required.
@return true if removal of code unit has been confirmed
Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/database/code/CodeUnitDB.java