Don't try to index empty documentation txt files
Don't try to index empty documentation txt files

If a documentation txt file has no content, parsing the document title
from it in the DocIndexer fails with a NullPointerException:

  Exception in thread "main" java.lang.NullPointerException
    at java.util.regex.Matcher.getTextLength(Matcher.java:1234)
    at java.util.regex.Matcher.reset(Matcher.java:308)
    at java.util.regex.Matcher.<init>(Matcher.java:228)
    at java.util.regex.Pattern.matcher(Pattern.java:1088)
    at DocIndexer.index(DocIndexer.java:117)
    at DocIndexer.invoke(DocIndexer.java:86)
    at DocIndexer.main(DocIndexer.java:163)

Change-Id: Idb4b808847d326ba49c9a2494a95b1cad8eb9406
Signed-off-by: Edwin Kempin <b444e279ad95fdef4fbdd82c813b624595df204a@sap.com>

netroby/gerrit,MerritCR/merrit,Team-OctOS/host_gerrit,TonyChai24/test,thinkernel/gerrit,gerrit-review/gerrit,Seinlin/gerrit,gcoders/gerrit,Distrotech/gerrit,thesamet/gerrit,Team-OctOS/host_gerrit,quyixia/gerrit,qtproject/qtqa-gerrit,TonyChai24/test,Distrotech/gerrit,thesamet/gerrit,jackminicloud/test,midnightradio/gerrit,anminhsu/gerrit,qtproject/qtqa-gerrit,netroby/gerrit,renchaorevee/gerrit,WANdisco/gerrit,Distrotech/gerrit,joshuawilson/merrit,gerrit-review/gerrit,Team-OctOS/host_gerrit,midnightradio/gerrit,jackminicloud/test,Overruler/gerrit,Team-OctOS/host_gerrit,joshuawilson/merrit,anminhsu/gerrit,jackminicloud/test,jackminicloud/test,MerritCR/merrit,supriyantomaftuh/gerrit,Overruler/gerrit,GerritCodeReview/gerrit,MerritCR/merrit,thesamet/gerrit,thinkernel/gerrit,anminhsu/gerrit,qtproject/qtqa-gerrit,renchaorevee/gerrit,quyixia/gerrit,WANdisco/gerrit,gerrit-review/gerrit,WANdisco/gerrit,midnightradio/gerrit,Distrotech/gerrit,netroby/gerrit,thesamet/gerrit,qtproject/qtqa-gerrit,WANdisco/gerrit,netroby/gerrit,gcoders/gerrit,supriyantomaftuh/gerrit,Overruler/gerrit,quyixia/gerrit,MerritCR/merrit,renchaorevee/gerrit,qtproject/qtqa-gerrit,Distrotech/gerrit,gerrit-review/gerrit,quyixia/gerrit,joshuawilson/merrit,joshuawilson/merrit,GerritCodeReview/gerrit,quyixia/gerrit,Overruler/gerrit,gerrit-review/gerrit,Team-OctOS/host_gerrit,hdost/gerrit,dwhipstock/gerrit,dwhipstock/gerrit,jackminicloud/test,gcoders/gerrit,Seinlin/gerrit,anminhsu/gerrit,qtproject/qtqa-gerrit,MerritCR/merrit,GerritCodeReview/gerrit,thinkernel/gerrit,anminhsu/gerrit,thinkernel/gerrit,TonyChai24/test,pkdevbox/gerrit,dwhipstock/gerrit,hdost/gerrit,thesamet/gerrit,thesamet/gerrit,WANdisco/gerrit,gerrit-review/gerrit,joshuawilson/merrit,TonyChai24/test,hdost/gerrit,thesamet/gerrit,pkdevbox/gerrit,supriyantomaftuh/gerrit,pkdevbox/gerrit,gcoders/gerrit,gcoders/gerrit,TonyChai24/test,jackminicloud/test,Overruler/gerrit,pkdevbox/gerrit,netroby/gerrit,Seinlin/gerrit,midnightradio/gerrit,Seinlin/gerrit,supriyantomaftuh/gerrit,quyixia/gerrit,qtproject/qtqa-gerrit,GerritCodeReview/gerrit,MerritCR/merrit,hdost/gerrit,Distrotech/gerrit,thinkernel/gerrit,Seinlin/gerrit,jackminicloud/test,supriyantomaftuh/gerrit,Distrotech/gerrit,renchaorevee/gerrit,WANdisco/gerrit,GerritCodeReview/gerrit,dwhipstock/gerrit,joshuawilson/merrit,netroby/gerrit,WANdisco/gerrit,midnightradio/gerrit,GerritCodeReview/gerrit,pkdevbox/gerrit,Overruler/gerrit,midnightradio/gerrit,gcoders/gerrit,Team-OctOS/host_gerrit,MerritCR/merrit,netroby/gerrit,gcoders/gerrit,thinkernel/gerrit,joshuawilson/merrit,hdost/gerrit,quyixia/gerrit,Seinlin/gerrit,dwhipstock/gerrit,Team-OctOS/host_gerrit,thinkernel/gerrit,renchaorevee/gerrit,gerrit-review/gerrit,TonyChai24/test,anminhsu/gerrit,TonyChai24/test,renchaorevee/gerrit,supriyantomaftuh/gerrit,supriyantomaftuh/gerrit,hdost/gerrit,GerritCodeReview/gerrit,GerritCodeReview/gerrit,joshuawilson/merrit,dwhipstock/gerrit,renchaorevee/gerrit,hdost/gerrit,MerritCR/merrit,pkdevbox/gerrit,pkdevbox/gerrit,dwhipstock/gerrit,Seinlin/gerrit,anminhsu/gerrit