public function validateNoUnmaintainedPhpVersionsInTravis($travisYml, $maintainedVersions)
    {
        if (empty($travisYml['php'])) {
            return true;
        }

        $failedTravis = array();
        // First pass - check the .travis.yml constraints against the maintained versions.
        foreach ($travisYml['php'] as $travisVersion) {
            if (!in_array($travisVersion, $maintainedVersions)) {
                $failedTravis[] = $travisVersion;
            }
        }

        if (!empty($failedTravis)) {
            $this->output->writeln(
                sprintf(
                    '<error>travis.yml specifies PHP version "%s" but only "%s" are actively maintained.</error>',
                    implode(', ', $failedTravis),
                    implode(', ', $maintainedVersions)
                )
            );

            return false;
        }

        return true;
    }