cannot build source on debian 10

I cannot build from source on Debian 10 buster, because the package depends on itself in a strange way.
I can fix the g++ dependency I am worried more about the openjdk-8-jdk that depends ona package of same name.

I created a new chroot.
reconfigured the locales
and now I get this error:

Code: Select all
    apt build-dep openjdk-8-jdk
    Reading package lists... Done
    Reading package lists... Done
    Building dependency tree
    Reading state information... Done
    Some packages could not be installed. This may mean that you have
    requested an impossible situation or if you are using the unstable
    distribution that some required packages have not yet been created
    or been moved out of Incoming.
    The following information may help to resolve the situation:

    The following packages have unmet dependencies:
     builddeps:openjdk-8-jdk : Depends: g++-9 but it is not installable
                               Depends: openjdk-8-jdk but it is not installable or
                                        openjdk-7-jdk but it is not installable
    E: Unable to correct problems, you have held broken packages.

This is how I created the chroot.

3642 [2020-06-15 13:40:04] sudo mkdir /stable-chroot
3643 [2020-06-15 13:40:13] sudo debootstrap stable /stable-chroot http://deb.debian.org/debian/
3653 [2020-06-15 13:41:30] cd /stable-chroot/
3654 [2020-06-15 13:41:30] sudo mount -t proc proc proc/
3655 [2020-06-15 13:41:30] sudo mount --rbind /sys sys/
3656 [2020-06-15 13:41:31] sudo mount --rbind /dev dev/
sudo chroot /stable-chroot/ /bin/bash

then dpkg-reconfigure locales which worked well

Here are my sources.list and preferences:

deb http://deb.debian.org/debian stable main
deb-src http://deb.debian.org/debian stable main

# stretch-backports, pinned 100 by default so that it does not install by default
deb http://ftp.debian.org/debian stretch-backports main contrib non-free

# Testing repository - main, contrib and non-free branches
deb http://ftp.se.debian.org/debian testing main contrib non-free
deb-src http://ftp.se.debian.org/debian testing main contrib non-free

# Testing security updates repository
deb http://security.debian.org/ testing-security main contrib non-free
deb-src http://security.debian.org/ testing-security main contrib non-free

# Unstable repo main, contrib and non-free branches, no security updates here
deb http://ftp.se.debian.org/debian unstable main non-free contrib
deb-src http://ftp.se.debian.org/debian unstable main non-free contrib

preferences;

#backports are pinnined at 100 by default
# if this is not negative, a dist-upgrade can move too many packages to the backports versions
Package: *
Pin: release a=stretch-backports
Pin-Priority: -4

Package: *
Pin: release a=testing
Pin-Priority: -5

Package: *
Pin: release a=unstable
Pin-Priority: -10