Family contains other families loaded into it but not used. Consider purging family document from unused families and types.
Namespace: Autodesk.Revit.DB
Assembly: RevitAPI (in RevitAPI.dll) Version: 26.1.0.0 (26.1.0.34)
Syntax
C#
public static FailureDefinitionId ManyUnusedNestedFamilies { get; }