code: public FormValidation doCheckIncludeRegex( @QueryParameter String value ) throws IOException, ServletException, InterruptedException  {
          String v = Util.fixEmpty(value);
          if (v != null) {
              try {
                  Pattern.compile(v);
              } catch (PatternSyntaxException pse) {
                  return FormValidation.error(pse.getMessage());
              }
          }
          return FormValidation.ok();
      }
docs: Checks if the include regular expression is valid.