Add Emission and Alpha inputs to Principled BSDF by Brecht (Cycles and Eevee):
I suppose that emission strength could be configured with some nodes connected to emission input. But would not it be convenient to be able to configure emission strength directly from Principled BSDF node?
Alex Strand completed last Brecht work on Principled BSDF by adding Emission Strength socket:
Change will be introduced in Blender 2.81