    # File lib/chef/cookbook/metadata.rb, line 481
          def self.validate_json(json_str)
            o = Chef::JSONCompat.from_json(json_str)
            metadata = new()
            VERSION_CONSTRAINTS.each do |method_name, hash_key|
              if constraints = o[hash_key]
               constraints.each do |cb_name, constraints|
                 metadata.send(method_name, cb_name, *Array(constraints))
               end
              end
            end
            true
          end