Added [at]method annotations

Related to https://scrutinizer-ci.com/g/phpDocumentor/phpDocumentor2/inspections/942c0aed-d89f-400c-bc9e-ef2a4fceee33/issues/files/src/phpDocumentor/Plugin/Core/Transformer/Writer/Graph.php?status=existing&selectedLabels[0]=9&orderField=path&order=asc