code: public FormValidation doViewExistsCheck(@QueryParameter String value) {
          checkPermission(View.CREATE);
  
          String view = Util.fixEmpty(value);
          if(view==null) return FormValidation.ok();
  
          if(Jenkins.getInstance().getView(view)!=null)
              return FormValidation.ok();
          else
              return FormValidation.error(Messages.ProxyView_NoSuchViewExists(value));
      }
docs: Fails if a global view with the given name does not exist.