public Allocation newChild(String description, long allocationUnits) {
    return new Allocation(description, allocationUnits, this);
  }
Creates a new child {@link Allocation} (sub-allocation).

@param description user-facing description of what the sub-allocation represents
@param allocationUnits number of allocation units the child holds
@return a new {@link Allocation}
jib-core/src/main/java/com/google/cloud/tools/jib/event/progress/Allocation.java