Cannot select multiple options on listbox

[naciriii]

Describe the bug

• It's not possible to select multiple options from listbox

To Reproduce

• Select a pdf that has a form with listbox field
• Fill the form with node-pdftk
• Attempt to select one option (works fine)

  pdftk
      .input('./my.pdf')
      .fillForm({
  'listbox': 'option1'
  })

  Matching FDF for field fill

  <<
  /V (option1)
  /T (listbox)
  >> 

• Attempt 1 to select two options (not working)

  pdftk
      .input('./my.pdf')
      .fillForm({
  'listbox': 'option1,option2'
  })

  Matching FDF

  <<
  /V (\(item1,item2\))
  /T (listbox)
  >> 

• Attempt 2 to select two options (not working)

  pdftk
      .input('./my.pdf')
      .fillForm({
  'listbox': ['option1','option2']
  })

  Matching FDF

  <<
  /V (item1,item2)
  /T (listbox)
  >>

  Expected behavior

• both options should be selected in the pdf

Desktop :

• OS: Linux Debian
• Version 11
• node-pdftk version: 0.14.0

Additional context

• Seamlessly, it's not possible to select multiple options of listbox with FDF, even after testing with pdftk from the cli it was not possible to select multiple options.
• Apparently with XFDF it's possible to select multiple options for a listbox with the following xml

  <?xml version="1.0" encoding="UTF-8"?>
  <xfdf xmlns="http://ns.adobe.com/xfdf/" xml:space="preserve">
  <fields>
  <field name="listbox">
  <value>option1</value>
  <value>option2</value>
  </field>
  </fields>
  </xfdf>