code: function Custom(properties) {
          if (properties)
              for (var keys = Object.keys(properties), i = 0; i < keys.length; ++i)
                  if (properties[keys[i]] != null)
                      this[keys[i]] = properties[keys[i]];
      }
docs: Properties of a Custom.
  @exports ICustom
  @interface ICustom
  @property {string} [key] Custom key
  @property {google.protobuf.IAny} [val] Custom val
   
  Constructs a new Custom.
  @exports Custom
  @classdesc Represents a Custom.
  @constructor
  @param {ICustom=} [properties] Properties to set