code: private void setup(ResetType resetType, Ref commitName) {
      CheckUtilities.checkNullArgument(resetType, "resetType");
      CheckUtilities.checkNullArgument(commitName, "commitName");
  
      this.resetType = resetType;
      this.commitName = commitName;
    }
docs: Central instance construction setup method.
  
  @param resetType
  The type of reset to perform.
  @param commitName
  The name of the commit to reset to.