Let’s say the document you want to build has characters (such as French braces) that are open or close delimiters. That is not a problem.
When DocumentBuilder finds an open and close delimiter, it grabs the value between the delimiters and passes it to the getValue method. If the getValue method returns null, then DocumentBuilder leaves that portion of the document template alone.
That means that you can have delimiters as part of your document, without any problems.
If, however, your document contains a large number of non-used delimiters, you might consider changing the delimiters. For example, if your delimiters are “<” and “>”, and you are building an XML document, performance may slow as DocumentBuilder must parse through all of them unnecessarily.