Support {0}.key/tag/value when comparing key values

[naoliv]

When using a test like this:

*["contact:phone" = *phone],
*["contact:fax" = *fax],
*["contact:website" = *website],
*["contact:email" = *email],
*["contact:facebook" = *facebook]
*["contact:twitter" = *twitter] {
        throwWarning: tr("{0} and {1} are the same", "{0.key}", "{1.key}");
}

we can see, for example, a warning with a null value: contact:phone and null are the same (even when using 1.tag or 1.value)

Could JOSM support key/tag/value for cases like this, please?

JOSM:

Repository Root: http://josm.openstreetmap.de/svn
Build-Date: 2015-10-15 01:32:10
Last Changed Author: Don-vip
Revision: 8882
Repository UUID: 0c6e7542-c601-0410-84e7-c038aed88b3b
Relative URL: ^/trunk
URL: http://josm.openstreetmap.de/svn/trunk
Last Changed Date: 2015-10-15 01:02:36 +0200 (Thu, 15 Oct 2015)
Last Changed Rev: 8882

Identification: JOSM/1.5 (8882 pt_BR) Linux Debian GNU/Linux unstable (sid)
Memory Usage: 554 MB / 3641 MB (337 MB allocated, but free)
Java version: 1.7.0_85, Oracle Corporation, OpenJDK 64-Bit Server VM
Java package: openjdk-7-jre:amd64-7u85-2.6.1-5
VM arguments: [-Dawt.useSystemAAFontSettings=on, -Dsun.java2d.opengl=true]
Dataset consistency test: No problems found

[Don-vip]

For this specific case you must use {0.value}:

*["contact:phone" = *phone],
*["contact:fax" = *fax],
*["contact:website" = *website],
*["contact:email" = *email],
*["contact:facebook" = *facebook]
*["contact:twitter" = *twitter] {
        throwWarning: tr("{0} and {1} are the same", "{0.key}", "{0.value}");
}

It would be too complex to change the underlying mechanism.