docs: public IExpressionBuilder addExpression() {
  		final IExpressionBuilder builder = this.expressionProvider.get();
  		builder.eInit(getXBlockExpression(), new Procedures.Procedure1<XExpression>() {
  					private int index = -1;
  					public void apply(XExpression it) {
  						if (this.index >= 0) {
  							getXBlockExpression().getExpressions().set(index, it);
  						} else {
  							getXBlockExpression().getExpressions().add(it);
  							this.index = getXBlockExpression().getExpressions().size() - 1;
  						}
  					}
  				}, getTypeResolutionContext());
  		return builder;
  	}