code: @Override
  	public PropertyDocument build() {
  		prepareBuild();
  		return factory.getPropertyDocument(
  				(PropertyIdValue) this.entityIdValue, this.labels,
  				this.descriptions, this.aliases, getStatementGroups(),
  				this.datatype, this.revisionId);
  	}
docs: Returns the {@link ItemDocument} that has been built.
  
  @return constructed item document
  @throws IllegalStateException
  if the object was built already