code: private void validateServerVariables(ValidationHelper helper, Context context, Set<String> variables, Server t) {
          ServerVariables serverVariables = t.getVariables();
  
          for (String variable : variables) {
              if (serverVariables == null || !serverVariables.containsKey(variable)) {
                  final String message = Tr.formatMessage(tc, "serverVariableNotDefined", variable);
                  helper.addValidationEvent(new ValidationEvent(ValidationEvent.Severity.ERROR, context.getLocation("variables"), message));
              }
          }
      }
docs: Ensures that all the serverVariables are defined
  
  @param helper the helper to send validation messages
  @param variables the set of variables to validate