A short survey (by no means statistically valid) of the top java projects on github, such as guava, mockito, junit, hadoop, etc. shows that these projects use one, or in rarer cases two build automation systems. Currently in the dev branch there are config files for three: maven, gradle and ant. I believe this will be very hard to maintain so one build system should be picked and the others removed.
A short survey (by no means statistically valid) of the top java projects on github, such as guava, mockito, junit, hadoop, etc. shows that these projects use one, or in rarer cases two build automation systems. Currently in the dev branch there are config files for three: maven, gradle and ant. I believe this will be very hard to maintain so one build system should be picked and the others removed.