I finally figured out why the warnings came. Groups (and maybe qmodules) have to be defined in a seperate file with qdoc extension, like

group1.qdoc
Qt Code:
  1. /*!
  2. \group group1
  3. \brief Brief description
  4.  
  5. Full description
  6.  
  7. */
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Putting this in a qml-file will not work. It will just be ignored. Thats not all. Files need to be defined in the config. In this case add
Qt Code:
  1. sources.fileextensions += *.qdocs
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