Replace 'tab' to 'space' characters in sources.

Comment:
you can see these files in sonar or
can use simple script to find these files (it needs to be runned from root dir of project):

for i in `find -path '*/src/main/*' -name '*.java'`; do if egrep -q $'\t' $i; then echo $i; fi; done

References:
http://sonar.jtalks.org/drilldown/violations/org.jtalks.poulpe:poulpe?rule=checkstyle%3Acom.puppycrawl.tools.checkstyle.checks.whitespace.FileTabCharacterCheck