code: public Reference setReferenceElement(IIdType theReference) {
      if (theReference != null) {
        setReference(theReference.getValue());
      } else {
        setReference(null);
      }
      return this;
    }
docs: Convenience setter which sets the reference to the complete {@link IIdType#getValue() value} of the given
  reference.
  
  @param theReference The reference, or <code>null</code>
  @return
  @return Returns a reference to this