Remove TextUnits which have no translatable text...

[Former user]

Original [issue 70](https://code.google.com/p/okapi/issues/detail?id=70) created by @ysavourel on 2009-05-12T16:38:13.000Z:

Currently the BaseFilter/MarkupFilters can produce TextUnits which have all whitespace or internal tags without translatable text. In some cases it would be desirable to convert these TextUnits to a DocumentPart so they are hidden from the translator.

[Former user]

Comment [1.](https://code.google.com/p/okapi/issues/detail?id=70#c1) originally posted by @ysavourel on 2009-06-23T17:19:49.000Z:

We decided that empty TextUnits are OK.