The source node in most cases contains the sample message as written by the developer. If it looks like a dot-delimitted string such as "form.label.firstname", then the developer has not provided a default message.

Admin Admin key: breadcrumb.admin Could not find Segment Group for '%identifier%' Nie można znaleźć Grupy Segmentów dla '%identifier%' key: Could not find Segment Group for '%identifier%' Could not find Segment for '%identifier%' Nie można znaleźć segmentu dla '%identifier%' key: Could not find Segment for '%identifier%'