@Override
	public String getComment(CommentType commentType) {
		if (commentType == null) {
			return null;
		}
		lock.acquire();
		try {
			checkIsValid();
			if (!checkedComments) {
				readComments();
			}
			if (commentRec == null) {
				return null;
			}
			return commentRec.getString(commentType.ordinal());
		}
		finally {
			lock.release();
		}
	}
@see ghidra.program.model.listing.CodeUnit#addOperandReference(int,
     ghidra.program.model.address.Address,
     ghidra.program.model.symbol.RefType, SourceType)
Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/database/code/CodeUnitDB.java