Ctrl+Backspace and Ctlr+Shift+Backspace emit the same character

**Context**
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I have successfully created following key-bindings:

- Ctrl+Delete to `kill-word` (i.e., delete from cursor to the end of next word),
- Ctrl+Shift+Delete to `kill-line` (i.e., delete from cursor to the end of the line),
- Ctrl+Backspace to `backward-kill-word` (i.e., delete from cursor to the beginning of previous word).

I want now to bind Ctrl+Shift+Backspace to `backward-kill-line` (i.e., delete from cursor to the beginning of the line).

**Problem**
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Ctrl+Backspace and Ctrl+Shift+Backspace emit the same character.

Indeed:
- Ctrl+C Ctrl+Backspace prints `^H`
- Ctrl+C Ctrl+Shift+Backspace prints `^H`

I think it should emits another character, just like:
- Ctrl+C Ctrl+Delete prints `^[[3;5~`
- Ctrl+C Ctrl+Shift+Delete prints `^[[3;6~`

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**Configuration**
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Guake Terminal: 3.5.1
VTE: 0.52.2
VTE runtime: 0.52.2
Gtk: 3.22.30
Distro: Ubuntu 18.04.2 LTS
GNOME: 3.28.2