code: @Override
      public ContextedRuntimeException addContextValue(final String label, final Object value) {
          exceptionContext.addContextValue(label, value);
          return this;
      }
docs: Adds information helpful to a developer in diagnosing and correcting the problem.
  For the information to be meaningful, the value passed should have a reasonable
  toString() implementation.
  Different values can be added with the same label multiple times.
  <p>
  Note: This exception is only serializable if the object added is serializable.
  </p>
  
  @param label  a textual label associated with information, {@code null} not recommended
  @param value  information needed to understand exception, may be {@code null}
  @return {@code this}, for method chaining, not {@code null}