Travis: run java tests sequentially...
Travis: run java tests sequentially...

or-tools/or-tools,or-tools/or-tools,or-tools/or-tools,google/or-tools,google/or-tools,google/or-tools,or-tools/or-tools,google/or-tools,google/or-tools,or-tools/or-tools,or-tools/or-tools,google/or-tools