Issue #2665992 by alexpott, klausi, heykarthikwithu, xjm, tstoeckler: @file is not required for classes, interfaces and traits

Issue #1392754 by tss, justAChris, jhodgdon: Comply with new documentation standards for @file for namespaced class files

Issue #1822048 by dawehner, tim.plunkett, damiankloip, EclipseGc, martin107, neclimdul: Introduce a generic fallback plugin mechanism.