add extra initialization checks for VirtualJetProducer with empty inputs (same as #13152 )

[slava77]

add extra initialization checks for short-cirquited cases with no inputs (effects not accounted in PR 11902 and 11820 in 76X)

Solves the HI job failures reported in
https://hypernews.cern.ch/HyperNews/CMS/get/recoDevelopment/1419.html

[cmsbuild]

A new Pull Request was created by @slava77 (Slava Krutelyov) for CMSSW_7_6_X.

It involves the following packages:

RecoJets/JetProducers

@cmsbuild, @cvuosalo, @davidlange6, @slava77 can you please review it and eventually sign? Thanks.
@rappoccio, @jdolen, @ahinzmann, @TaiSakuma, @yslai, @nhanvtran, @schoef, @mariadalfonso this is something you requested to watch as well.
@slava77, @Degano, @smuzaffar you are the release manager for this.

cms-bot commands are list here #13028

[slava77]

@cmsbuild please test

[cmsbuild]

The tests are being triggered in jenkins.
https://cmssdt.cern.ch/jenkins/job/ib-any-integration/10898/console

[cmsbuild]

+1
Tested at: a6b647b
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-13153/10898/summary.html

[cmsbuild]

Comparison is ready
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-13153/10898/summary.html

[slava77]

+1

for #13153 a6b647b

• the same fix as in add extra initialization checks for VirtualJetProducer with empty inputs #13152: the same issue with crashes on empty inputs should appear in 76X as well
• jenkins tests pass and show no differences vs baseline

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next CMSSW_7_6_X IBs (tests are also fine). This pull request requires discussion in the ORP meeting before it's merged. @slava77, @davidlange6, @Degano, @smuzaffar

[davidlange6]

+1