/**
  * Sets the new trim specification.
  *
  * @param specification The new trim specification; <code>null</code> is not valid
  */
 public void setSpecification(Specification specification) {
   Assert.isNotNull(specification, "The Specification cannot be null");
   Specification oldSpecification = this.specification;
   this.specification = specification;
   firePropertyChanged(SPECIFICATION_PROPERTY, oldSpecification, specification);
 }
 private void validateOrdering(Ordering ordering) {
   Assert.isNotNull(ordering, "The Ordering cannot be null");
 }