docs: public void setStrictlyCoLocatedWith(JobVertex strictlyCoLocatedWith) {
  		if (this.slotSharingGroup == null || this.slotSharingGroup != strictlyCoLocatedWith.slotSharingGroup) {
  			throw new IllegalArgumentException("Strict co-location requires that both vertices are in the same slot sharing group.");
  		}
  
  		CoLocationGroup thisGroup = this.coLocationGroup;
  		CoLocationGroup otherGroup = strictlyCoLocatedWith.coLocationGroup;
  
  		if (otherGroup == null) {
  			if (thisGroup == null) {
  				CoLocationGroup group = new CoLocationGroup(this, strictlyCoLocatedWith);
  				this.coLocationGroup = group;
  				strictlyCoLocatedWith.coLocationGroup = group;
  			}
  			else {
  				thisGroup.addVertex(strictlyCoLocatedWith);
  				strictlyCoLocatedWith.coLocationGroup = thisGroup;
  			}
  		}
  		else {
  			if (thisGroup == null) {
  				otherGroup.addVertex(this);
  				this.coLocationGroup = otherGroup;
  			}
  			else {
  				// both had yet distinct groups, we need to merge them
  				thisGroup.mergeInto(otherGroup);
  			}
  		}
  	}