[BEAM-4418] Fix duplicate source set declaration conflict.
[BEAM-4418] Fix duplicate source set declaration conflict.

apache/beam,apache/beam,charlesccychen/incubator-beam,lukecwik/incubator-beam,markflyhigh/incubator-beam,charlesccychen/beam,charlesccychen/beam,charlesccychen/beam,apache/beam,lukecwik/incubator-beam,rangadi/beam,chamikaramj/beam,RyanSkraba/beam,lukecwik/incubator-beam,RyanSkraba/beam,iemejia/incubator-beam,rangadi/beam,lukecwik/incubator-beam,robertwb/incubator-beam,lukecwik/incubator-beam,robertwb/incubator-beam,robertwb/incubator-beam,robertwb/incubator-beam,markflyhigh/incubator-beam,robertwb/incubator-beam,markflyhigh/incubator-beam,lukecwik/incubator-beam,robertwb/incubator-beam,markflyhigh/incubator-beam,charlesccychen/beam,apache/beam,apache/beam,apache/beam,chamikaramj/beam,rangadi/beam,apache/beam,mxm/incubator-beam,apache/beam,mxm/incubator-beam,markflyhigh/incubator-beam,charlesccychen/beam,rangadi/incubator-beam,rangadi/beam,chamikaramj/beam,charlesccychen/incubator-beam,robertwb/incubator-beam,chamikaramj/beam,RyanSkraba/beam,RyanSkraba/beam,rangadi/beam,lukecwik/incubator-beam,rangadi/beam,RyanSkraba/beam,lukecwik/incubator-beam,chamikaramj/beam,rangadi/beam,RyanSkraba/beam,apache/beam,charlesccychen/incubator-beam,chamikaramj/beam,rangadi/incubator-beam,chamikaramj/beam,robertwb/incubator-beam,lukecwik/incubator-beam,chamikaramj/beam,chamikaramj/beam,iemejia/incubator-beam,apache/beam,robertwb/incubator-beam,rangadi/incubator-beam,apache/beam,RyanSkraba/beam,robertwb/incubator-beam,charlesccychen/beam,charlesccychen/beam,lukecwik/incubator-beam,markflyhigh/incubator-beam,chamikaramj/beam,markflyhigh/incubator-beam