docs: @Trivial
      public static String getSymbol(String s) {
          String outputSymbol = null;
          if (s != null) {
              if (s.length() > 3) {
                  // ${} .. look for $
                  int pos = s.indexOf('$');
                  if (pos >= 0) {
                      // look for { after $
                      int pos2 = pos + 1;
                      if (s.length() > pos2) {
                          if (s.charAt(pos2) == '{') {
                              // look for } after {
                              pos2 = s.indexOf('}', pos2);
                              if (pos2 >= 0) {
                                  outputSymbol = s.substring(pos, pos2 + 1);
                              }
                          }
                      }
                  }
              }
          }
          return outputSymbol;
      }