Add new property for ROOT SharedWriter to allow setting of min number of events per write

This will avoid in-efficiency when creating dynamic branches on the single SharedWriter.

This merge request affects 1 package:

• Database/AthenaPOOL/AthenaPoolCnvSvc

Adding @ssnyder ,@mnowak as watchers

added Database master review-pending-level-1 labels

CI Result SUCCESS (hash 4fc22104)

	Athena	AthSimulation	AthGeneration	AnalysisBase
externals
cmake
make
required tests
optional tests

Full details available on this CI monitor view
Athena: number of compilation errors 0, warnings 0
AthSimulation: number of compilation errors 0, warnings 0
AthGeneration: number of compilation errors 0, warnings 0
AnalysisBase: number of compilation errors 0, warnings 0
For experts only: Jenkins output [CI-MERGE-REQUEST-CC7 21713]

added review-approved label and removed review-pending-level-1 label

merged

mentioned in commit fefe3a4c

added sweep:ignore label