Dropping jdk11 on travis for the time being.
Dropping jdk11 on travis for the time being.

RoaringBitmap/RoaringBitmap,lemire/RoaringBitmap,lemire/RoaringBitmap,RoaringBitmap/RoaringBitmap,RoaringBitmap/RoaringBitmap,lemire/RoaringBitmap,lemire/RoaringBitmap,RoaringBitmap/RoaringBitmap