When using the Pipeline syntax in a running Jenkins instance, the pipeline fragment generated for git by the checkout step always includes:

doGenerateSubmoduleConfigurations: false

That is the default value. The pipeline syntax user interface provides no way to change that value and there are no automated tests for a non-default value.

doGenerateSubmoduleConfigurations: false should be removed from the pipeline syntax output because it is a default value.

Likewise for submoduleCfg