Default values set in function signatures are missing in output

In testing the output from QDoc with the comments file feature, it seems default values set in function signatures is missing from the generated output. See e.g.  qtxml/qxmlreader.html [0], where the = nullptr bit is removed.

[0] - https://git.qt.io/paulwicking/comment-file-output/blob/master/qtxml/qxmlreader.html