code: protected static String valueString(Object value) {
          if (value == null) {
              return "null";
          } else if (value instanceof String) {
              return "\"" + ((String) value).codePoints()
                      .flatMap(cp ->
                          (cp == '"')
                              ? "\\\"".codePoints()
                              : (cp < 256)
                                  ? charRep[cp].codePoints()
                                  : IntStream.of(cp))
                      .collect(
                              StringBuilder::new,
                              StringBuilder::appendCodePoint,
                              StringBuilder::append)
                      .toString() + "\"";
          } else if (value instanceof Character) {
              char cp = (char) (Character) value;
              return "'" + (
                  (cp == '\'')
                      ? "\\\'"
                      : (cp < 256)
                              ? charRep[cp]
                              : String.valueOf(cp)) + "'";
          } else if (value.getClass().isArray()) {
              int dims = 0;
              Class<?> t = value.getClass();
              while (true) {
                  Class<?> ct = t.getComponentType();
                  if (ct == null) {
                      break;
                  }
                  ++dims;
                  t = ct;
              }
              String tn = t.getTypeName();
              int len = Array.getLength(value);
              StringBuilder sb = new StringBuilder();
              sb.append(tn.substring(tn.lastIndexOf('.') + 1, tn.length()));
              sb.append("[");
              sb.append(len);
              sb.append("]");
              for (int i = 1; i < dims; ++i) {
                  sb.append("[]");
              }
              sb.append(" { ");
              for (int i = 0; i < len; ++i) {
                  sb.append(valueString(Array.get(value, i)));
                  if (i < len - 1) {
                      sb.append(", ");
                  }
              }
              sb.append(" }");
              return sb.toString();
          } else {
              return value.toString();
          }
      }
docs: Converts the {@code Object} value from
  {@link ExecutionControl#invoke(String, String)  } or
  {@link ExecutionControl#varValue(String, String)   } to {@code String}.
  
  @param value the value to convert
  @return the {@code String} representation