skip empty lines in JetCorrectorParameters ctor

[missirol]

PR description:

While testing with the class JetCorrectorDBWriter, I encountered a seg-fault coming from JetCorrectorParameters.

What led to the crash was the fact that the input .txt file I was using had an empty line in it (afaik, empty lines are absent in standard JEC txt files, thus no crashes).

This PR applies a quick fix, skipping empty lines in JetCorrectorParameters, and making the sw a bit more robust; a more sophisticated fix is left to experts of this package [*].

No changes expected.

FYI: @lathomas @kirschen @juska @glatino @pallabidas @sparedes

[*] The core issue is that the ctor of JetCorrectorParameters::Record does not throw an error if the input string has an invalid format (e.g. empty); in those cases, the mMin/mMax vectors are not filled, and accessing xMin(i) later on here leads to a crash.

PR validation:

Validated with private tests.

[cmsbuild]

+code-checks

Logs: https://cmssdt.cern.ch/SDT/code-checks/cms-sw-PR-32387/20253

• This PR adds an extra 16KB to repository

[cmsbuild]

A new Pull Request was created by @missirol (Marino Missiroli) for master.

It involves the following packages:

CondFormats/JetMETObjects

@ggovi, @cmsbuild, @santocch can you please review it and eventually sign? Thanks.
@mmarionncern, @ahinzmann, @rappoccio, @jdamgov, @jdolen, @nhanvtran, @gkasieczka, @clelange, @schoef, @mmusich, @mariadalfonso, @seemasharmafnal this is something you requested to watch as well.
@silviodonato, @dpiparo, @qliphy you are the release manager for this.

cms-bot commands are listed here

[santocch]

please test

[cmsbuild]

+1
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-6514be/11341/summary.html
CMSSW: CMSSW_11_3_X_2020-12-04-1100
SCRAM_ARCH: slc7_amd64_gcc900

[cmsbuild]

Comparison results are now available
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-6514be/11341/summary.html
CMSSW: CMSSW_11_3_X_2020-12-04-1100
SCRAM_ARCH: slc7_amd64_gcc900

Comparison Summary:

• No significant changes to the logs found
• Reco comparison results: 4 differences found in the comparisons
• DQMHistoTests: Total files compared: 35
• DQMHistoTests: Total histograms compared: 2529593
• DQMHistoTests: Total failures: 7
• DQMHistoTests: Total nulls: 0
• DQMHistoTests: Total successes: 2529564
• DQMHistoTests: Total skipped: 22
• DQMHistoTests: Total Missing objects: 0
• DQMHistoSizes: Histogram memory added: 0.0 KiB( 34 files compared)
• Checked 148 log files, 37 edm output root files, 35 DQM output files

[santocch]

+1

[silviodonato]

merge
@ggovi please let us know if you agree, it seems a trivial fix