DeltaGenerateCommandBase is an extension of the RunnableCommand contract (from Spark SQL) for runnable commands that getPath.

Read up on RunnableCommand in The Internals of Spark SQL online book.
DeltaGenerateCommand is the default and only known DeltaGenerateCommandBase in Delta Lake.

Getting Path Of Delta Table From Table Identifier — getPath Method

  spark: SparkSession,
  tableId: TableIdentifier): Path


getPath is used when DeltaGenerateCommand is requested to run.