The version service provides assistance for next minor / major numbering, but you must always explicitly set the CURRENT version label otherwise it will be missing.
versionService.checkout( toVersionIds, options );
DataPackage versioned = versionService.checkin( toVersion, VersionStrategy.NEXT_MINOR, false, Arrays.asList( new String[]{"CURRENT"} ), options );
This will implement the 1.0 -> 1.1 or with VersionStrategy.NEXT_MAJOR 1.0 -> 2.0