code: @Override
      public ContextedRuntimeException setContextValue(final String label, final Object value) {
          exceptionContext.setContextValue(label, value);
          return this;
      }
docs: Sets 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.
  Any existing values with the same labels are removed before the new one is added.
  <p>
  Note: This exception is only serializable if the object added as value 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}