federation mapping debug has useless direct_maps information

Fix proposed to branch: master
Review: https://review.opendev.org/678700

I was able to confirm this using the following data:

$ cat input
NAME: lbragstad
EMAIL: <email address hidden>
GROUPS: development
$ cat mapping.json
{
"rules": [
        {
            "local": [
                {
                    "user": {
                        "name": "{0}",
                        "email": "{1}"
                    },
                    "group": {
                        "name": "{2}",
                        "domain": {
                            "id": "default"
                        }
                    }
                }
            ],
            "remote": [
                {
                    "type": "NAME"
                },
                {
                    "type": "EMAIL"
                },
                {
                    "type": "GROUPS"
                }
            ]
        }
]
}

Debug logging https://pasted.tech/pastes/3804094968c6aae429bd43da60efbe9fa7d6272c.raw when running:

$ keystone-manage mapping_engine --rules mapping.json --input input --engine-debug

Fix proposed to branch: master
Review: https://review.opendev.org/679139

Change abandoned by Lance Bragstad (<email address hidden>) on branch: master
Review: https://review.opendev.org/679139
Reason: Rolled this into https://review.opendev.org/#/c/678700/4

Reviewed: https://review.opendev.org/678700
Committed: https://git.openstack.org/cgit/openstack/keystone/commit/?id=b33abb4b070d72c16af914e4292adb205bdee5fa
Submitter: Zuul
Branch: master

commit b33abb4b070d72c16af914e4292adb205bdee5fa
Author: John Dennis <email address hidden>
Date: Mon Aug 26 19:32:22 2019 -0400

    Federation mapping debug should show direct_maps values

    If you use keystone-manage mapping_engine --engine-debug to test your
    rules (or when debug logging is on during run time) the diagnostic
    output fails to emit a piece of crucial information, the contents
    direct map array. What you'll get instead is this:

    direct_maps: <keystone.federation.utils.DirectMaps object at 0x7f7121887b00>

    That's because the DirectMaps class does not have a __str__() method
    and Python resorts to __ref__() in the absence of __str__() and all
    __ref__() does is print the class name and it's memory location, not
    very useful.

    This patch adds a __str__() method to the DirectMaps class so the
    debug output now includes the actual direct map data like this:

    direct_maps: [['<email address hidden>'], ['Group1', 'Group3']]

    Co-Authored-By: Lance Bragstad <email address hidden>
    Change-Id: I07643fbe3e1e712b7eac716a7f671a2d513e920b
    Closes-Bug: 1841486
    Signed-off-by: John Dennis <email address hidden>

This issue was fixed in the openstack/keystone 16.0.0.0rc1 release candidate.