Is there any way to determine which field is required at fieldset level in Apex

Users are not permitted to approve a record that they have submitted themselves for approval Trigger on this scenario 

I am generating XML files with the help of apex code in Salesforce but after the generation of the XML file. file print the blank element and attribute, so I want to avoid the blank element and attribute at the time of XML file generation, for example, I am creating an account object there are 10 fields on the account object and I have filled only 4 required fields, after that, I am generating the XML file-related the same account but the XML file shows all 10 fields, 4 fields that I am filled and other 6 blank fields, so I want to generate the XML file On filled fields only(I want to show only 4 fields that I am filled on account object) so How to Avoid The blank Element and attribute at the time of XML file generation.