Get a data key value for each resolved package.

        Args:
            key (str): String key of property, eg 'tools'.
            request_only (bool): If True, only return the key from resolved
                packages that were also present in the request.

        Returns:
            Dict of {pkg-name: (variant, value)}.

def get_key(self, key, request_only=False):
        """Get a data key value for each resolved package.

        Args:
            key (str): String key of property, eg 'tools'.
            request_only (bool): If True, only return the key from resolved
                packages that were also present in the request.

        Returns:
            Dict of {pkg-name: (variant, value)}.
        """
        values = {}
        requested_names = [x.name for x in self._package_requests
                           if not x.conflict]

        for pkg in self.resolved_packages:
            if (not request_only) or (pkg.name in requested_names):
                value = getattr(pkg, key)
                if value is not None:
                    values[pkg.name] = (pkg, value)

        return values