regression fix + workaround in our own code

Change-Id: Iea1bc3d40b39d29cc58938e274eed92cf6dce9ce
Reviewed-on: https://git.eclipse.org/r/c/jdt/eclipse.jdt.core/+/179457
Tested-by: Stephan Herrmann <stephan.herrmann@berlin.de>
Reviewed-by: Stephan Herrmann <stephan.herrmann@berlin.de>