code: function validateEnvironment(environment, envContext, source = null) {
  
      // not having an environment is ok
      if (!environment) {
          return;
      }
  
      Object.keys(environment).forEach(env => {
          if (!envContext.get(env)) {
              const message = `${source}:\n\tEnvironment key "${env}" is unknown\n`;
  
              throw new Error(message);
          }
      });
  }
docs: Validates an environment object
  @param {Object} environment The environment config object to validate.
  @param {Environments} envContext Env context
  @param {string} source The name of the configuration source to report in any errors.
  @returns {void}