In the GATK Best Practices WDL in github, the GenotypeGVCFs commandline does not specify any interval padding via -ip or --interval-padding parameter.
https://github.com/gatk-workflows/gatk4-germline-snps-indels/blob/master/joint-discovery-gatk4.wdl
(as of commit d9fea5462f148ab3a49a177ddd328ede304f4f62).
However, this old guide from 2017 recommends interval padding of 100bp:
https://software.broadinstitute.org/gatk/documentation/article?id=11062
What is the recommended practice for interval padding for HaplotypeCaller and GenotypeGVCFs v4.x?