docs: protected String ensureContainerKeyword(EObject grammarContainer) {
  		final Iterator<Keyword> iterator = Iterators.filter(grammarContainer.eContents().iterator(), Keyword.class);
  		if (iterator.hasNext()) {
  			return iterator.next().getValue();
  		}
  		return getExpressionConfig().getFieldContainerDeclarationKeyword();
  	}