How to decrease space between ExpansionPanel elements in Flutter?

This is my code:

ExpansionPanel(
headerBuilder: (BuildContext context, bool isExpanded) {
  return SizedBox(
      //height: 20,
      child: ListTile(
        title: Text("Files (2)"),
        leading: Icon(Icons.folder_outlined),
        minLeadingWidth : 4,
        contentPadding: EdgeInsets.symmetric(vertical: 0.0, horizontal: 16.0),
      ),
  );
},
body: Column(
  children: [
    ListTile(
      title: Text("File_0"),
      leading: Icon(Icons.insert_drive_file),
      minLeadingWidth : 4,
      contentPadding: EdgeInsets.symmetric(vertical: 0.0, horizontal: 16.0),
    ),
    ListTile(
      title: Text("File_1"),
      leading: Icon(Icons.insert_drive_file),
      minLeadingWidth : 4,
      contentPadding: EdgeInsets.symmetric(vertical: 0.0, horizontal: 16.0),
    )
  ],
),
isExpanded: items[0].isExpanded,
),

And this is the result:

As you see the distance between Folder and files and between files is huge. Could anyone say how to decrease this distance?

>Solution :

You can modify the space/padding on ExpansionPanelList calling expandedHeaderPadding.

ExpansionPanelList(
  expandedHeaderPadding: EdgeInsets.zero,
  children: [
    ExpansionPanel(

listTile provide default height based on

maxHeight: (isDense ? 48.0 : 56.0) + densityAdjustment.dy,

You can create custom row widget for this.

ExpansionPanel(
  headerBuilder: (BuildContext context, bool isExpanded) {
    return ListTile(
      title: Text("Files (2)"),
      leading: Icon(Icons.folder_outlined),
      minLeadingWidth: 4,
      contentPadding:
          EdgeInsets.symmetric(vertical: 0.0, horizontal: 0.0),
    );
  },
  body: Column(
    children: [
      ...List.generate(
          3,
          (index) => Padding(
                padding: const EdgeInsets.only(left: 8.0, top: 4),
                child: Row(
                  //decorate items the way you like
                  children: [
                    Icon(Icons.insert_drive_file),
                    SizedBox(
                      width: 16,
                    ),
                    Text("File_$index"),
                  ],
                ),
              ))
    ],
  ),
  isExpanded: true,
),

More about expandedHeaderPadding and ExpansionPanelList on flutter.dev.