docs: @Override
      public boolean isReadOnly(ELContext context)
              throws PropertyNotFoundException, ELException {
          EvaluationContext ctx = new EvaluationContext(context, this.fnMapper,
                  this.varMapper);
          context.notifyBeforeEvaluation(getExpressionString());
          boolean result = this.getNode().isReadOnly(ctx);
          context.notifyAfterEvaluation(getExpressionString());
          return result;
      }