# File lib/r10k/deployment.rb, line 88
    def validate!
      hash = {}
      sources.each do |source|
        source.environments.each do |environment|
          if hash.key?(environment.path)
            osource, oenvironment = hash[environment.path]
            msg = ""
            msg << "Environment collision at #{environment.path} between "
            msg << "#{source.name}:#{environment.name} and #{osource.name}:#{oenvironment.name}"
            raise R10K::R10KError, msg
          else
            hash[environment.path] = [source, environment]
          end
        end
      end
    end