title: Maven goal to append lines to file
body: <p>The context is that before compile, there is a goal to download a .proto (Google Protobuffer) file to have generated files after. In this proto file there is no package mentioned and so when the classes get generated they do not appear to any correct package so can't be imported and used.</p>
  
  <p>A proto file here may be considered as a simple text file. I have a very specific need - I want to add some text at the beginning of this file.</p>
  
  <p>Is it possible to do using maven?</p>
  
  <p>Thank you.</p>