gistfile1.js

/*

inspired from this sources https://jqueryui.com/autocomplete/#xml

*/

$(function() {

      var mydata = [];

      $.ajax({
          url: "{{YOUR GOOGLE WEB SERVICE URL WHICH RETURNS JSON}}",
          dataType: "jsonp",
          success: function(data) {

              $(data.{{ GOOGLE SHEET NAME }}).each(function() { // MAY VARY DEPENDS ON YOUR JSON OUTCOME
                  var record = this.NAME + " - " + this.VALUE; // THIS LINE DEPENDS ON YOUR JSON OUTCOME
                  mydata.push(record);
              });

              $("#request_custom_fields_24212885").autocomplete({  // USE YOUR TICKET FIELD REFERENCE
                  source: mydata,
                  minLength: 0,
                  select: function(event, ui) {
                        $("#request_custom_fields_24212885").val( ui.item.value ); // THIS SHOULD SET THE VALUE ONCE YOU MADE A CHOICE
                  }
              });
          }
      });
  });